CN108528192B - Hybrid power system based on open winding motor and power distribution method thereof - Google Patents

Abstract

The invention relates to a hybrid power system based on an open winding motor and a power distribution method, wherein the hybrid power system comprises an engine, a battery, a generator, the open winding motor, a first inverter, a second inverter, a main reducer and a control system, the engine can be in transmission connection with the generator, the output end of the generator can be electrically connected with the input end of the battery and/or one end of the second inverter under the control of the control system, so that the electric energy output by the generator can charge the battery, the output end of the battery is electrically connected with one end of the first inverter, the other end of the first inverter is electrically connected with the first input end of the open winding motor, so that the battery can supply power to the first inverter to supply power to the open winding motor, the other end of the second inverter is electrically connected with the second input end of the open winding motor, so that the engine can supply power to the second inverter when driving the generator to supply power to the open winding motor, and the output end of the open winding motor is in transmission connection with the main reducer.

Description

Hybrid power system based on open winding motor and power distribution method thereof

Technical Field

The invention relates to the technical field of automobile hybrid power, in particular to a hybrid power system based on an open winding motor and a power distribution method of the hybrid power system based on the open winding motor.

Background

This section provides background information related to the present disclosure only and is not necessarily prior art.

In the face of increasingly severe energy situation and environmental protection pressure in the global scope, new energy automobiles become a new growth point in the market. The pure electric vehicle has the advantages of zero pollution, high energy conversion efficiency and the like, but the cost performance of the pure electric vehicle cannot compete with that of a traditional engine vehicle due to the problems of high battery cost, low endurance mileage and the like. The hybrid electric vehicle can fully exert the advantages of an engine vehicle and an electric vehicle, can reduce fuel consumption and improve driving range, and becomes a feasible scheme for solving the problems of energy conservation and environmental protection at the present stage.

In general, a hybrid vehicle is a vehicle having 2 or more than 2 kinds of energy sources for driving energy, and many HEVs including an engine, a motor, and a battery pack are being studied. Existing hybrid vehicles typically employ a DC/DC voltage converter and are typically equipped with a transmission or the like, which results in higher vehicle cost and additional power loss, reducing drive system efficiency. In addition, because the traditional motor adopts a single inverter, the voltage level of the system is higher, and the number of the batteries which are connected in series is also higher.

Disclosure of Invention

The object of the present invention is to solve at least one of the problems of the prior art mentioned above, and the object is achieved by the following technical solutions:

according to one aspect of the invention, a hybrid system based on an open winding motor is provided, the hybrid system comprises an engine, a battery, a generator, the open winding motor, a first inverter, a second inverter, a main reducer and a control system, wherein the engine can be in transmission connection with the generator, an output end of the generator can be electrically connected with an input end of the battery and/or one end of the second inverter under the control of the control system, so that electric energy output by the generator can charge the battery, an output end of the battery is electrically connected with one end of the first inverter, the other end of the first inverter is electrically connected with a first input end of the open winding motor, so that the battery can supply power to the first inverter so as to supply power to the open winding motor, and the other end of the second inverter is electrically connected with a second input end of the open winding motor, so that the engine can supply power to the second inverter so as to supply power to the open winding motor (simultaneously, electric energy output by the generator can also charge the battery) when driving the generator, and an output end of the open winding motor is in transmission connection with the main reducer.

The hybrid power system according to the invention brings the following beneficial technical effects:

the two power sources respectively provide energy for the open-winding motor to drive the motor to rotate, and the torque output by the motor is transmitted to the rear driving wheel through the main speed reducer, so that the driving of the whole vehicle is realized; a gearbox assembly is cancelled, so that the vehicle cost is reduced; the power system can be powered by adopting double energy sources, different power combinations among different energy sources can be realized, the original DC/DC voltage converter is eliminated, and the design cost is reduced; compared with the traditional motor controlled by a single inverter, the motor with the open winding can effectively reduce the voltage of a direct current bus, thereby reducing the number of series nodes of a power storage battery and reducing the voltage level of a system.

Further, the open winding motor is a motor as follows: the method comprises the steps of opening a neutral point connected with a Y-shaped winding of the induction motor and dividing six lead wires at two ends of the neutral point into two groups, wherein the first group of the two groups is connected with the first inverter, and the second group of the two groups is connected with the second inverter.

According to another aspect of the present invention, there is provided a power distribution method of a hybrid system based on the open-winding motor, the power distribution method including the steps of:

s1: determining parameters for each component, including: determining an upper limit value SOC of a battery state of charge SOC _max And a lower limit value SOC _min And determines the battery power P _b Maximum charge and discharge power P _b-max And minimum charging and discharging power P _b-min (ii) a Determining battery capacity Q _b Internal resistance R of the battery _b Open circuit voltage U _o (ii) a Determining torque T for open winding electric machines _M Maximum torque T of _M-max And a minimum torque T _M-min Rotating speed w of open winding motor _M Maximum rotational speed w of _M-max And a minimum rotation speed w _M-min Rated current I of motor of open winding motor _Mmax (ii) a Determining the torque T of an engine _ICE Maximum torque T of _ICE-max And a minimum torque T _ICE-min Engine speed w _ICE Maximum rotational speed w of _ICE-max And a minimum rotation speed w _ICE-min (ii) a Determining the speed ratio of a main speed reducer; determining the oil consumption map of the engine;

s2: partitioning the SOC feasible region, comprising: determining constraints, i.e. SOC, of a battery, an engine and an open-winding machine _min ≤SOC≤SOC _max ，P _b-min ≤P _b ≤P _b-max ，w _ICE-min ≤w _ICE ≤w _ICE-max ，T _ICE-min ≤T _ICE ≤T _ICE-max ，w _M-min ≤w _M ≤w _M-max ，T _M-min ≤T _M ≤T _M-max (ii) a Constraining the initial SOC and the final SOC of the battery to remain the same, i.e. SOC _start ＝SOC _terminal In which SOC is _start Represents the initial SOC value, SOC _terminal Represents the SOC value at the final state; slave SOC _start 、SOC _terminal The two ends are respectively charged and discharged with the maximum charge and discharge power P of the battery _b-max Charging and discharging are carried out until a set upper limit value SOC is reached _max And a lower limit value SOC _min The enclosed area is the feasible area S;

s3: discretizing the feasible region S, comprising: discretizing time along the driving circulation direction, setting the time discrete step length as 1 second, dividing the work circulation into N step lengths, taking the right end point of each step length to form N discrete system states, and recording x (k) as the kth system state, wherein k is more than or equal to 1 and less than or equal to N; discretizing the battery charge state SOC in the feasible region S in the time step after discretization, and setting the SOC (k) at the position x (k) _max Is the maximum SOC value, SOC (k), over the feasible region at x (k) _min For the minimum SOC value over the feasible region at x (k), let the discrete size be

Where m (k) represents the SOC (k) when the system state is x (k) _max 、SOC(k) _max The average value between the two is m (k); discretizing SOC into m +1 points in a feasible region at x (k), and taking SOC (k, n) as x (k) from SOC (k) _max N is more than or equal to 1 and less than or equal to m +1 from the nth discrete point from top to bottom; within the feasible region S, since the SOC does not vary drastically between the adjacent system states, it is assumed that the open-circuit voltage U of the battery is _o The maximum allowable power during discharging of the battery is P _discharmax By use of I _discharmax Represents P _discharmax Corresponding to the discharge current, when the system state is x (k), a certain discrete point is set as SOC (k, n), and the maximum charging power P during charging _charmax Method for recovering maximum charging power P allowed when battery is charged by dividing braking energy _charmax1 And the maximum charging power P allowed when the battery is charged by the engine _charmax2 I.e. during charging, P _charmax Expressed as: p _charmax ＝max(P _charmax1 ,P _charmax2 ) By use of I _charmax Represents its charging current;

s4: calculating an engine oil consumption matrix: charging and discharging I _charmax 、I _discharmax After the determination, the SOC variation range of the discrete point SOC (k, n) is determined, and the maximum SOC variation value is delta SOC _max (k, n), i.e. Δ SOC _max (k, n) is the calculation range of the engine oil consumption matrix at the discrete point SOC (k, n), and the whole driving cycle is traversed and calculated to obtain the oil consumption matrix;

s5: and solving the power distribution track according to the oil consumption matrix.

The power distribution method according to the invention brings the following beneficial technical effects:

according to the invention, the SOC feasible region is reasonably discretized, and the oil consumption matrix is calculated based on the discretization and the power distribution track is solved, so that the driving cycle accumulated oil consumption is minimum, and the global optimization of energy management is realized; the power distribution method obviously reduces the calculated amount in the aspect of SOC dynamic programming and simplifies DP (dynamic programming) operation, thereby reducing the calculated amount, shortening the calculation time and obviously improving the battery energy programming capability.

Further, in step S3: Δ (k) is obtained by a dichotomy comprising the steps of:

let m (k) =1, calculate

By the value of Δ (k) and Δ SOC _max (k, n) comparing;

if delta (k) is less than or equal to delta SOC _max (k, n), obtaining m (k) when the system state is x (k), namely, obtaining the SOC (k) when the system state is x (k) _max 、SOC(k) _min The average value is m (k);

if Δ (k) > Δ SOC _max (k, n), let m (k) = m (k) +1, calculate

If also Δ (k) > Δ SOC _max (k, n), continuing to make m (k) = m (k) +1, and circulating until delta (k) ≦ delta SOC _max When (k, n) is reached, the calculation is stopped to obtain the final m (k), and at the moment, when the system state is x (k), the SOC (k) is obtained _max 、SOC(k) _min The average value between the two is m (k) parts.

Further, in step S3:

when P is present _charmax ＝P _charmax1 At the point SOC (k, n), horizontal lines l, I are set to keep the SOC value constant _charmax Forms an included angle theta with the horizontal line l ₁ ，I _discharmax Forms an angle theta with the horizontal line l ₂ Then at this time I _charmax And I _discharmax Asymmetric about the horizontal line l, when theta ₁ ＜θ ₂ ；

When P is present _charmax ＝P _charmax2 At this time I _charmax And I _discharmax Symmetrical about the horizontal line l, the two processes being inverse to each other, in which case θ ₁ ＝θ ₂ 。

Further, step S4 includes:

let SOC (k +1, j) be Δ SOC from SOC (k, n) to system state x (k + 1) _max A point in the range of (k, n) which changes the system state from SOC (k, n) at x (k) to SOC (k +1, j) at x (k + 1)The middle SOC (k, n) is the starting point of the change process, and u (k, n, j) is used to represent the control quantity when changing from SOC (k, n) to SOC (k +1, j), wherein u (k, n, j) passes through P _b (k, n, j) and P _ICE (k, n, j) to control, P _b (k, n, j) and P _ICE (k, n, j) respectively represent a battery power and an engine power required to change from the SOC (k, n) to the SOC (k +1, j);

at Δ SOC based on the determined set of achievable states for SOC _max (k, n) determining the battery power P by _b ：

Wherein, P _b As the power of the battery, R _b Is the internal resistance of the battery, Q _b Is the battery capacity, U _o Is an open circuit voltage;

according to the calibrated cycle working condition, the required power of the whole vehicle at each system state x (k) can be obtained and is marked as P _req (k) Then the open winding motor power P (k) = P _req (k)；

The power required by the engine is obtained by subtracting the battery power from the power required by the whole vehicle, namely P _ICE (k,n,j)＝P _req (k)-P _b (k,n,j)；

And comparing the fuel consumption matrix calculation according to the power distribution requirement to judge so as to obtain a corresponding engine fuel consumption value.

Further, in step S4: let the power distribution demand ratio be r (k, n, j) = P _{Inverse r1} (k,n,j)/P _{Inverse r2} (k, n, j) wherein P _{Inverse r1} (k,n,j)、P _{Inverse r2} (k, n, j) are the power demands of the first and second inverters respectively when changing from discrete point SOC (k, n) to SOC (k +1, j), where P _{Inverse r1} (k,n,j)＝P _b (k,n,j)，P _{Inverse r2} (k,n,j)＝P _ICE (k, n, j) characterizing the required power distribution capability of the open-winding machine when changing from SOC (k, n) to SOC (k +1, j) by two inverter power demand distribution ratios;

setting power distribution ratio r (k) = P of open winding motor _{Inverse 1} (k)/P _{Inverse 2} (k) In which P is _{Inverse 1} (k)、P _{Inverse 2} (k) Power of the first inverter and power of the second inverter, i.e. P, respectively, when the system state is at x (k) _{Inverse 1} (k)＝P _b (k)，P _{Inverse 2} (k)＝P _ICE (k)；

Maximum power distribution ratio r of motor for maximum power distribution capacity of open winding motor _max (k) Is expressed as the maximum value of r (k), r _max (k)∈[0，1]By r _max (k) Representing the maximum power output capability of the first inverter and the second inverter of the open-winding electric machine in this system state,

establishing maximum power distribution ratio r of open winding motor _max (k) Map graph as a function of system state;

define fuel (k, n, j) as the value of fuel consumption of the engine when changing from SOC (k, n) to SOC (k +1, j), which represents the fuel consumption of the engine in this process.

Further, the motor power distribution ratio is determined as follows:

when changing from SOC (k, n) to SOC (k +1, j), the power distribution demand ratio r (k, n, j) > r _max (k) When the system state is in the state, the motor cannot distribute the output torque according to the required power, the failure control set is adopted, the oil consumption value fuel (k, n, j) of the engine is recorded as + ∞, and the motor torque T is _M (k, n, j) and motor speed w _M (k, n, j) is 0, and the battery power and the engine power at this time are respectively represented by P _b (k,n,j)＝0，P _ICE (k,n,j)＝0；

When the power distribution demand ratio r (k, n, j) is less than or equal to r _max (k) And then, the system state does not exceed the limit of the distribution capacity of the open winding motor, the oil consumption of the engine is subjected to table lookup through the established oil consumption map of the engine, and the economic area b with the lowest oil consumption rate is selected according to the required power at each moment _e (k) Obtaining the oil consumption value fuel (k, n, j) of the engine under a certain working condition, and respectively recording the battery power and the engine power at the moment as P _b (k,n,j)、P _ICE (k,n,j)；

When the system state is changed from SOC (k, n) to SOC (k +1, j), determining to obtain fuel consumption values fuel (k, n, j) according to the power distribution ratio, and setting a set consisting of all the fuel consumption values fuel (k, n, j) at x (k) as the fuel consumption set fuel (k) at x (k) of the system state in the feasible region S, wherein the corresponding battery power and the corresponding engine power P are the fuel consumption set fuel (k) at x (k) of the system state in the feasible region S _b (k,n,j)、P _ICE The set of (k, n, j) is P _b (k)、P _ICE (k)；

And recording the oil consumption matrix as F = { fuel (k) |1 ≦ k ≦ N }.

Further, step S5 includes:

the optimization objective to minimize the cumulative fuel consumption of the driving cycle is expressed as:

when the system state is x (k), and k is more than or equal to 1 and less than or equal to N, the recursion equation is set as follows:

J _k ＝min[fuel(SOC(k),P _b (k),P _ICE (k))+J _k+1 ((SOC(k))]in the formula J _k Representing the accumulated minimum oil consumption from the k step to the N step;

reversely pushing from the termination state to the initial state by a recursive calling mode, completing a traversal optimization searching process, and obtaining a power distribution track which enables oil consumption to be minimum;

the minimum oil consumption power distribution track sequence is recorded as:

U＝argmin[fuel(SOC(k),P _b (k),P _ICE (k))+J _k+1 ((SOC(k))]。

further, before the determination of the motor power distribution ratio, preliminary screening is performed on the discrete points at x (k + 1), including the following steps:

maximum allowable discharge power of battery at x (k) of system state

The corresponding maximum discharge current of the battery is->

Setting the maximum discharge coefficient allowed by the battery at x (k) in the system state

Set at point SOC (k, n) horizontal line l, I keeping SOC value constant _charmax Forms an angle theta with the horizontal line l ₁ ，I _discharmax Forms an included angle theta with the horizontal line l ₂ Then, then

Forms an included angle theta with the horizontal line l ₃ ＝k×θ ₂ The system state is a calculation range Δ SOC from a certain discrete point SOC (k, n) on x (k) to a discrete point SOC on x (k + 1) _max (k, n) is reduced to

Through preliminary screening, discrete points that are not reached by SOC (k, n) are excluded, and the points are determined

The power distribution ratio is determined, thereby reducing the amount of calculation and shortening the calculation time.

Drawings

Various additional advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic diagram of an open winding electric machine based hybrid powertrain according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method of power distribution for an open winding electric machine based hybrid powertrain according to an embodiment of the present invention;

fig. 3 schematically illustrates the division of the feasible region S of the power allocation method according to an embodiment of the present invention;

fig. 4 schematically shows a discretization process of a feasible region S of the power allocation method according to an embodiment of the invention;

FIG. 5 schematically shows a feasible region S at P of a power allocation method according to an embodiment of the present invention _charmax ＝P _charmax1 Time Δ SOC _max (k，n)；

FIG. 6 schematically shows a feasible region S at P of a power allocation method according to an embodiment of the present invention _charmax ＝P _charmax2 Time Δ SOC _max (k，n)；

Fig. 7 schematically shows a change process of u (k, n.j) when the system state changes from SOC (k, n) at x (k) to SOC (k +1, j) at x (k + 1)) according to the power allocation method of the embodiment of the present invention;

fig. 8 schematically shows a maximum power distribution ratio r of an open winding motor according to a power distribution method of an embodiment of the present invention _max (k) Map graph that varies with system state (operating condition);

fig. 9 schematically shows a schematic diagram of preliminary screening of discrete points at x (k + 1) according to the power allocation method of the embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

As shown in fig. 1, according to an embodiment of the present invention, there is provided an open-winding motor-based hybrid system 100, the hybrid system 100 includes an engine 10, a battery 20, a generator 30, an open-winding motor 40, a first inverter 51, a second inverter 52, a final drive 60, and a control system (not shown), wherein the engine 10 is drivingly coupled to the generator 30, an output of the generator 30 is electrically connectable to an input of the battery 20 and/or an end of the second inverter 52 under the control of the control system (e.g., controlled according to different power requirements of the hybrid system), as shown by a charging line indicated by a dashed line in fig. 1, so that electric power output from the generator 30 can charge the battery 20, an output of the battery 20 is electrically connected to one end of the first inverter 51, another end of the first inverter 51 is electrically connected to a first input of the open-winding motor 40, so that the battery 20 can supply electric power to the open-winding motor 40, another end of the second inverter 52 is electrically connected to a second input of the open-winding motor 40, as shown by a solid line in fig. 1, so that the second inverter 40 can supply electric power to the open-winding motor 40, and the open-winding motor 10 is electrically connected to the final drive motor 40, as shown by a solid line in fig. 1, so that the open-winding motor 10 is electrically connected to power output of the open-winding motor 10.

The hybrid power system according to the invention brings the following beneficial technical effects: a gearbox assembly is cancelled, so that the vehicle cost is reduced; the power system can be supplied with power by adopting double energy sources, different power combinations among different energy sources can be realized, the original DC/DC voltage converter is eliminated, and the design cost is reduced; compared with the traditional motor controlled by a single inverter, the motor with the open winding can effectively reduce the voltage of a direct current bus, thereby reducing the number of series nodes of a power storage battery and reducing the voltage level of a system.

In addition, the final drive 50 may be in driving connection with a driving wheel 71 and a driving wheel 72, wherein the driving wheel may be a rear wheel or a front wheel.

Further, the open-winding motor 40 is a motor as follows: the neutral point to which the Y-winding of the induction machine is connected is opened and the six lead wires at both ends of the neutral point are divided into two groups, the first of the two groups being connected to the first inverter 51 and the second of the two groups being connected to the second inverter 52.

Referring now to fig. 1 to 9, a power distribution method of a hybrid system based on the above-mentioned open winding motor according to another aspect of the present invention is described, the power distribution method including the steps of:

s1: determining parameters for each component, including: determining an upper limit value SOC of a battery state of charge SOC _max And a lower limit value SOC _min (i.e., upper and lower limits of the battery working space) and determining the battery power P _b Maximum charge and discharge power P of _b-max And minimum charging and discharging power P _b-min (ii) a Determining battery capacity Q _b Internal resistance R of the battery _b Open circuit voltage U _o (simplifying the battery model into an equivalent circuit consisting of a voltage source and a resistor, not considering the influence of temperature change on the performance, and simultaneously neglecting a transient process caused by the existence of internal capacitance, and assuming that the characteristics of the charging and discharging processes are the same); determining torque T for open winding machines _M Maximum torque T of _M-max And a minimum torque T _M-min Rotating speed w of open winding motor _M Maximum rotational speed w of _M-max And a minimum rotational speed w _M-min Rated current I of motor of open winding motor _Mmax (ii) a Determining the torque T of an engine _ICE Maximum torque T of _ICE-max And a minimum torque T _ICE-min Rotational speed w of engine _ICE Maximum rotational speed w of _ICE-max And a minimum rotational speed w _ICE-min (ii) a Determining the speed ratio of a main speed reducer; determining the oil consumption map of the engine;

s2: partitioning the SOC feasible region, comprising: determining constraints, i.e. SOC, of a battery, an engine and an open-winding machine _min ≤SOC≤SOC _max ，P _b-min ≤P _b ≤P _b-max ，w _ICE-min ≤w _ICE ≤w _ICE-max ，T _ICE-min ≤T _ICE ≤T _ICE-max ，w _M-min ≤w _M ≤w _M-max ，T _M-min ≤T _M ≤T _M-max (ii) a Constraining the initial and final SOC of the battery to remain the same, i.e. SOC _start ＝SOC _terminal Wherein SOC is _start Represents the SOC value at the initial time,SOC _terminal represents the SOC value at the final state; slave SOC _start 、SOC _terminal The two ends are respectively charged and discharged with the maximum charge and discharge power P of the battery _b-max Charging and discharging are carried out until a set upper limit value SOC is reached _max And a lower limit value SOC _min The enclosed area is a feasible area S, as shown in fig. 3; it should be noted that the rotation speed and torque of the engine, the rotation speed and torque of the motor, etc. can be measured by conventional sensors and input into the control system, and therefore, the detailed description thereof is omitted.

S3: discretizing the feasible region S, including: discretizing time along the driving circulation direction, setting the time discrete step length as 1 second, dividing the work circulation into N step lengths, taking the right end point of each step length to form N discrete system states, and recording x (k) as the kth system state, wherein k is more than or equal to 1 and less than or equal to N; discretizing the battery charge state SOC in the feasible region S in the time step after discretization, and setting the SOC (k) at the position x (k) _max Is the maximum SOC value, SOC (k), over the feasible region at x (k) _min For the minimum SOC value over the feasible region at x (k), let the discrete size be

Where m (k) represents the SOC (k) when the system state is x (k) _max 、SOC(k) _max The average value between the two is m (k); dispersing the SOC into m +1 points in the feasible region at x (k), and taking the SOC (k, n) as x (k) from the SOC (k) _max The nth discrete point from top to bottom, wherein n is more than or equal to 1 and less than or equal to m +1, as shown in FIG. 4; within the feasible region S, since the SOC does not vary drastically between the adjacent system states, it is assumed that the open-circuit voltage U of the battery is _o The maximum allowable power during discharging of the battery is P _discharmax By use of I _discharmax Is represented by P _discharmax When the system state is x (k), the corresponding discharging current is set as SOC (k, n) at a certain discrete point, and the maximum charging power P is charged _charmax Method for recovering maximum charging power P allowed when battery is charged by dividing braking energy _charmax1 And the maximum charging power P allowed when the battery is charged by the engine _charmax2 I.e. during charging, P _charmax Expressed as: p is _charmax ＝max(P _charmax1 ,P _charmax2 ) By use of I _charmax Represents its charging current;

s4: calculating an engine oil consumption matrix: charging and discharging of I _charmax 、I _discharmax After the determination, the SOC variation range of the discrete point SOC (k, n) is determined, and the maximum SOC variation value is delta SOC _max (k, n), i.e. Δ SOC _max (k, n) is the calculation range of the engine oil consumption matrix at the discrete point SOC (k, n), and the whole driving cycle is traversed and calculated to obtain the oil consumption matrix;

s5: and solving a power distribution track according to the oil consumption matrix.

The power distribution method according to the invention brings the following beneficial technical effects: according to the invention, the SOC feasible region is reasonably discretized, the oil consumption matrix is calculated based on the discretization, and the power distribution track is solved, so that the driving cycle accumulated oil consumption is minimum, and the global optimization of energy management is realized; the power distribution method is accurate and efficient, the calculated amount in the aspect of SOC dynamic planning is obviously reduced, and DP operation is simplified, so that the calculation time is shortened, and the comprehensive efficiency of battery energy planning calculation is obviously improved.

Further, in step S3: Δ (k) is obtained by a dichotomy comprising the steps of:

let m (k) =1, calculate

By the value of Δ (k) and Δ SOC _max (k, n) comparing;

if delta (k) is less than or equal to delta SOC _max (k, n), obtaining m (k) when the system state is x (k), namely, obtaining the SOC (k) when the system state is x (k) _max 、SOC(k) _min The average value between the two is m (k);

if Δ (k) > Δ SOC _max (k, n), let m (k) = m (k) +1, calculate

If also Δ (k) > Δ SOC _max (k, n), continuing to make m (k) = m (k) +1, and circulating until delta (k) ≦ delta SOC _max When (k, n) is reached, the calculation is stopped to obtain the final m (k), and at the moment, when the system state is x (k), the SOC (k) is obtained _max 、SOC(k) _min The average value between the two is m (k).

Further, in step S3:

when P is present _charmax ＝P _charmax1 At point SOC (k, n), horizontal lines l, I are set to keep the SOC value constant _charmax Forms an included angle theta with the horizontal line l ₁ ，I _discharmax Forms an angle theta with the horizontal line l ₂ Then at this time I _charmax And I _discharmax Asymmetric about horizontal line l, when θ ₁ ＜θ ₂ As shown in fig. 5;

when P is _charmax ＝P _charmax2 At this time I _charmax And I _discharmax Symmetrical about the horizontal line l, the two processes being inverse to each other, in which case θ ₁ ＝θ ₂ As shown in fig. 6.

Further, step S4 includes:

let SOC (k +1, j) be Δ SOC from SOC (k, n) to system state x (k + 1) _max (k, n) when the system state changes from SOC (k, n) at x (k) to SOC (k +1, j) at x (k + 1), where SOC (k, n) is the starting point of the change process, and u (k, n, j) represents the control quantity when changing from SOC (k, n) to SOC (k +1, j), where u (k, n, j) passes P _b (k, n, j) and P _ICE (k, n, j) to control, P _b (k, n, j) and P _ICE (k, n, j) respectively indicate the battery power and the engine power required to change from SOC (k, n) to SOC (k +1, j), as shown in FIG. 7;

at Δ SOC based on the determined set of achievable states for SOC _max (k, n) determining the battery power P by _b ：

Wherein, P _b Is the battery power, R _b Is the internal resistance of the battery, Q _b Is the battery capacity, U _o Is an open circuit voltage;

according to a calibrated cycleWorking condition, the required power of the whole vehicle at each system state x (k) can be obtained and is marked as P _req (k) Then the open winding motor power P (k) = P _req (k)；

The power required by the engine is obtained by subtracting the power of the battery from the power required by the whole vehicle, namely P _ICE (k,n,j)＝P _req (k)-P _b (k,n,j)；

And comparing the fuel consumption matrix calculation according to the power distribution requirement to judge so as to obtain a corresponding engine fuel consumption value.

It should be noted that, due to the limitation of the distribution capability of the open winding motor, the oil consumption matrix needs to be calculated and determined according to the power distribution ratio, so as to obtain the corresponding oil consumption value of the engine.

Further, in step S4:

let the power distribution demand ratio be r (k, n, j) = P _{Inverse r1} (k,n,j)/P _{Inverse r2} (k, n, j) wherein P _{Inverse r1} (k,n,j)、P _{Inverse r2} (k, n, j) are the power demands of the first and second inverters, respectively, when changing from the discrete point SOC (k, n) to SOC (k +1, j), where P _{Inverse r1} (k,n,j)＝P _b (k,n,j)，P _{Inverse r2} (k,n,j)＝P _ICE (k, n, j) characterizing the required power distribution capability of the open-winding machine when changing from SOC (k, n) to SOC (k +1, j) by two inverter power demand distribution ratios;

setting power distribution ratio r (k) = P of open winding motor _{Inverse 1} (k)/P _{Inverse 2} (k) In which P is _{Inverse 1} (k)、P _{Inverse 2} (k) Power of the first inverter and power of the second inverter, i.e. P, respectively, when the system state is at x (k) _{Inverse 1} (k)＝P _b (k)，P _{Inverse 2} (k)＝P _ICE (k)；

Maximum power distribution ratio r of motor for maximum power distribution capacity of open winding motor _max (k) Is expressed as the maximum value of r (k), r _max (k)∈[0，1]By r, using _max (k) Representing the maximum power output capability of the first inverter and the second inverter of the open-winding machine in the system state,

establishing maximum power distribution ratio r of open winding motor _max (k) Map as a function of system state, as shown in FIG. 8;

defining fuel (k, n, j) as the engine fuel consumption value when SOC (k, n) changes to SOC (k +1, j), and representing the engine fuel consumption of the process.

Further, the motor power distribution ratio is determined as follows:

when changing from SOC (k, n) to SOC (k +1, j), the power distribution demand ratio r (k, n, j) > r _max (k) When the system state is in the state, the motor cannot distribute the output torque according to the required power, the failure control set is adopted, the oil consumption value fuel (k, n, j) of the engine is recorded as + ∞, and the motor torque T is _M (k, n, j) and Motor speed w _M (k, n, j) is 0, and the battery power and the engine power at this time are respectively represented by P _b (k,n,j)＝0，P _ICE (k,n,j)＝0；

When the power distribution demand ratio r (k, n, j) is less than or equal to r _max (k) And then, the system state does not exceed the limit of the distribution capacity of the open winding motor, the oil consumption of the engine is subjected to table lookup through the established oil consumption map of the engine, and the economic area b with the lowest oil consumption rate is selected according to the required power at each moment _e (k) Obtaining the oil consumption value fuel (k, n, j) of the engine under a certain working condition, and respectively recording the battery power and the engine power at the moment as P _b (k,n,j)、P _ICE (k,n,j)；

When the system state is changed from SOC (k, n) to SOC (k +1, j), determining to obtain fuel consumption values fuel (k, n, j) according to the power distribution ratio, and setting a set consisting of all the fuel consumption values fuel (k, n, j) at x (k) as the fuel consumption set fuel (k) at x (k) of the system state in the feasible region S, wherein the corresponding battery power and the corresponding engine power P are the fuel consumption set fuel (k) at x (k) of the system state in the feasible region S _b (k,n,j)、P _ICE The set of (k, n, j) is P _b (k)、P _ICE (k)；

And recording the oil consumption matrix as F = { fuel (k) |1 ≦ k ≦ N }.

Further, step S5 includes:

the optimization objective to minimize the cumulative fuel consumption of the driving cycle is expressed as:

when the system state is x (k), and k is more than or equal to 1 and less than or equal to N, the recursion equation is set as follows:

J _k ＝min[fuel(SOC(k),P _b (k),P _ICE (k))+J _k+1 ((SOC(k))]in the formula J _k Representing the cumulative minimum oil consumption from the k step to the N step;

reversely pushing from the termination state to the initial state by a recursive calling mode, finishing a traversal optimization searching process and obtaining a power distribution track which enables the oil consumption to be minimum;

the minimum oil consumption power distribution track sequence is recorded as:

U＝argmin[fuel(SOC(k),P _b (k),P _ICE (k))+J _k+1 ((SOC(k))]the sequence U may be stored to facilitate control of system calls.

Further, before the determination of the motor power distribution ratio, preliminary screening is performed on the discrete points at x (k + 1), including the following steps:

maximum allowable discharge power of battery at x (k) of system state

The corresponding maximum discharge current of the battery is->

Setting the maximum discharge coefficient of the battery at x (k) under the system state

Set at point SOC (k, n) a horizontal line l, I that keeps the SOC value constant _charmax Forms an included angle theta with the horizontal line l ₁ ，I _discharmax Forms an angle theta with the horizontal line l ₂ Then, then

Forms an angle theta with the horizontal line l ₃ ＝k×θ ₂ As shown in FIG. 9, the system state is a calculation range Δ SOC from a certain discrete point SOC (k, n) on x (k) to a discrete point SOC on x (k + 1) _max (k, n) is decreased to ^ greater than or equal to>

Through preliminary screening, discrete points that are not reached by SOC (k, n) are excluded, and the points are determined

The power distribution ratio is determined, thereby reducing the amount of calculation and shortening the calculation time.

It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. The terms "comprises," "comprising," "includes," "including," and "having" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order described or illustrated, unless specifically identified as an order of performance.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context.

While the invention has been described with reference to specific preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (8)

1. A power distribution method for a hybrid system based on an open-winding motor, wherein the hybrid system comprises an engine, a battery, a generator, the open-winding motor, a first inverter, a second inverter, a main reducer and a control system, wherein the engine can be in transmission connection with the generator, an output end of the generator can be electrically connected with an input end of the battery and/or one end of the second inverter under the control of the control system, so that the battery can be charged by electric energy output by the generator, an output end of the battery is electrically connected with one end of the first inverter, the other end of the first inverter is electrically connected with a first input end of the open-winding motor, so that the battery can supply power to the first inverter to supply power to the open-winding motor, the other end of the second inverter is electrically connected with a second input end of the open-winding motor, so that the engine can supply power to the second inverter to supply power to the open-winding motor when driving the generator, an output end of the open-winding motor is in transmission connection with the main reducer, and the open-winding motor is as follows: the method for distributing the power comprises the following steps of opening a neutral point connected with a Y-shaped winding of an induction motor and dividing six leads at two ends of the neutral point into two groups, wherein the first group of the two groups is connected with a first inverter, and the second group of the two groups is connected with a second inverter:

s1: determining parameters for each component, including: determining an upper limit value SOC of a state of charge SOC of a battery _max And a lower limit value SOC _min And determining the battery power P _b Maximum charge and discharge power P _b-max And minimum charging and discharging power P _b-min (ii) a Determining battery capacity Q _b Internal resistance R of the battery _b Open circuit voltage U _o (ii) a Determining torque T for open winding machines _M Maximum torque T of _M-max And a minimum torque T _M-min Rotating speed w of open winding motor _M Maximum rotational speed w of _M-max And a minimum rotation speed w _M-min Rated current I of motor of open winding motor _Mmax (ii) a Determining the torque T of an engine _ICE Maximum torque T of _ICE-max And a minimum torque T _ICE-min Engine speed w _ICE Maximum rotational speed w of _ICE-max And a minimum rotation speed w _ICE-min (ii) a Determining the speed ratio of a main speed reducer; determining the oil consumption map of the engine;

s2: partitioning the SOC feasible region, comprising: determining constraints, i.e. SOC, of a battery, an engine and an open-winding machine _min ≤SOC≤SOC _max ，P _b-min ≤P _b ≤P _b-max ，w _ICE-min ≤w _ICE ≤w _ICE-max ，T _ICE-min ≤T _ICE ≤T _ICE-max ，w _M-min ≤w _M ≤w _M-max ，T _M-min ≤T _M ≤T _M-max (ii) a Constraining the initial SOC and the final SOC of the battery to remain the same, i.e. SOC _start ＝SOC _terminal Wherein SOC is _start Representing the initial SOC value, SOC _terminal Represents the SOC value at the final state; slave SOC _start 、SOC _terminal The two ends are respectively charged and discharged with the maximum charge and discharge power P of the battery _b-max Charging and discharging are carried out until a set upper limit value SOC is reached _max And a lower limit value SOC _min The enclosed area is the feasible area S;

s3: discretizing the feasible region S, comprising: discretizing time along the driving circulation direction, setting the time discrete step length as 1 second, dividing the work circulation into N step lengths, taking the right end point of each step length to form N discrete system states, and recording x (k) as the kth system state, wherein k is more than or equal to 1 and less than or equal to N; discretizing the battery charge state SOC in the feasible region S in the time step after discretization, and setting the SOC (k) at the position x (k) _max Is the maximum SOC value, SOC (k), over the feasible region at x (k) _min For the minimum SOC value over the feasible region at x (k), let the discrete size be

Wherein m (k) represents the SOC (k) when the system state is x (k) _max 、SOC(k) _max The average value between the two is m (k); dispersing the SOC into m +1 points in the feasible region at x (k), and taking the SOC (k, n) as x (k) from the SOC (k) _max The nth discrete point from top to bottom, wherein n is more than or equal to 1 and less than or equal to m +1; within the feasible region S, since the SOC does not vary drastically between the adjacent system states, it is assumed that the open-circuit voltage U of the battery is _o The maximum allowable power during discharging of the battery is P _discharmax By use of I _discharmax Represents P _discharmax When the system state is x (k), the corresponding discharging current is set as SOC (k, n) at a certain discrete point, and the maximum charging power P is charged _charmax Method for recovering maximum charging power P allowed when battery is charged by dividing braking energy _charmax1 And the maximum charging power P allowed when the battery is charged by the engine _charmax2 I.e. during charging, P _charmax Expressed as: p is _charmax ＝max(P _charmax1 ,P _charmax2 ) By use of I _charmax Represents its charging current;

s4: calculating an engine oil consumption matrix: charging and discharging of I _charmax 、I _discharmax After the determination, the SOC variation range of the discrete point SOC (k, n) is determined, and the maximum SOC variation value is delta SOC _max (k, n), i.e. Δ SOC _max (k, n) is the calculation range of the engine oil consumption matrix at the discrete point SOC (k, n), and the whole driving cycle is traversed and calculated to obtain the oil consumption matrix;

s5: and solving the power distribution track according to the oil consumption matrix.

2. The power distribution method of an open-winding motor-based hybrid powertrain according to claim 1, wherein in step S3: Δ (k) is obtained by a dichotomy comprising the steps of:

let m (k) =1, calculate

By the value of Δ (k) and ΔSOC _max (k, n) comparing;

if delta (k) is less than or equal to delta SOC _max (k, n), obtaining m (k) when the system state is x (k), namely, obtaining the SOC (k) when the system state is x (k) _max 、SOC(k) _min The average value between the two is m (k);

if Δ (k) > Δ SOC _max (k, n), let m (k) = m (k) +1, calculate

If also Δ (k) > Δ SOC _max (k, n), continuing to make m (k) = m (k) +1, and circulating until delta (k) ≦ delta SOC _max When (k, n) is reached, the calculation is stopped to obtain the final m (k), and at the moment, when the system state is x (k), the SOC (k) is obtained _max 、SOC(k) _min The average value between the two is m (k).

3. The power distribution method of an open-winding motor-based hybrid powertrain according to claim 1, wherein in step S3:

when P is present _charmax ＝P _charmax1 At point SOC (k, n), horizontal lines l, I are set to keep the SOC value constant _charmax Forms an angle theta with the horizontal line l ₁ ，I _discharmax Forms an included angle theta with the horizontal line l ₂ Then I at this time _charmax And I _discharmax Asymmetric about horizontal line l, when θ ₁ ＜θ ₂ ；

When P is present _charmax ＝P _charmax2 At this time I _charmax And I _discharmax Symmetrical about the horizontal line l, the two processes being inverse to each other, in which case θ ₁ ＝θ ₂ 。

4. The power distribution method of the open-winding motor-based hybrid power system according to claim 2, wherein the step S4 comprises:

let SOC (k +1, j) be Δ SOC from SOC (k, n) to system state x (k + 1) _max (k, n) at a point in the range when the system state changes from SOC (k, n) at x (k) to SOC (k +1, j) at x (k + 1), where SOC (k, n) is the changeThe starting point of the process is represented by u (k, n, j) which passes through P, and represents the amount of control in the transition from SOC (k, n) to SOC (k +1, j) _b (k, n, j) and P _ICE (k, n, j) to control, P _b (k, n, j) and P _ICE (k, n, j) respectively represent a battery power and an engine power required to change from the SOC (k, n) to the SOC (k +1, j);

at Δ SOC based on the determined set of achievable states for SOC _max Determining the battery power P in the range of (k, n) by the following equation _b ：

Wherein, P _b As the power of the battery, R _b Is the internal resistance of the battery, Q _b Is the battery capacity, U _o Is an open circuit voltage;

according to the calibrated cycle working condition, the required power of the whole vehicle at each system state x (k) can be obtained and is marked as P _req (k) Then the open winding motor power P (k) = P _req (k)；

The power required by the engine is obtained by subtracting the battery power from the power required by the whole vehicle, namely P _ICE (k,n,j)＝P _req (k)-P _b (k,n,j)；

And comparing the power distribution requirement with the fuel consumption matrix for judgment to obtain a corresponding engine fuel consumption value.

5. The power distribution method of an open-winding motor-based hybrid powertrain according to claim 4,

in step S4: let the power distribution demand ratio be r (k, n, j) = P _{Inverse r1} (k,n,j)/P _{Inverse r2} (k, n, j) wherein P _{Inverse r1} (k,n,j)、P _{Inverse r2} (k, n, j) are the power demands of the first and second inverters, respectively, when changing from the discrete point SOC (k, n) to SOC (k +1, j), where P _{Inverse r1} (k,n,j)＝P _b (k,n,j)，P _{Inverse r2} (k,n,j)＝P _ICE (k, n, j) and two inverter power demand distribution ratios are used for representing the requirement of the open winding motor when the SOC (k, n) is changed to the SOC (k +1, j)The power distribution capability is obtained;

setting power distribution ratio r (k) = P of open winding motor _{Inverse 1} (k)/P _{Inverse 2} (k) In which P is _{Inverse 1} (k)、P _{Inverse 2} (k) Power of the first inverter and power of the second inverter, i.e. P, respectively, when the system state is at x (k) _{Inverse 1} (k)＝P _b (k)，P _{Inverse 2} (k)＝P _ICE (k)；

Maximum power distribution ratio r of motor for maximum power distribution capacity of open winding motor _max (k) Is expressed as the maximum value of r (k), r _max (k)∈[0，1]By r, using _max (k) Representing the maximum power output capability of the first inverter and the second inverter of the open-winding machine in the system state,

establishing maximum power distribution ratio r of open winding motor _max (k) Map as a function of system state;

define fuel (k, n, j) as the value of fuel consumption of the engine when changing from SOC (k, n) to SOC (k +1, j), which represents the fuel consumption of the engine in this process.

6. The power distribution method of the hybrid system based on the open-winding motor according to claim 5, wherein the motor power distribution ratio is determined as follows:

when changing from SOC (k, n) to SOC (k +1, j), the power distribution demand ratio r (k, n, j) > r _max (k) When the system state is in the state, the motor cannot distribute the output torque according to the required power, the failure control set is adopted, the oil consumption value fuel (k, n, j) of the engine is recorded as + ∞, and the motor torque T is _M (k, n, j) and motor speed w _M (k, n, j) is 0, and the battery power and the engine power at this time are respectively P _b (k,n,j)＝0，P _ICE (k,n,j)＝0；

When the power distribution demand ratio r (k, n, j) is less than or equal to r _max (k) Indicating that the system state does not exceed the open winding motor distribution capacityLimiting, wherein the oil consumption of the engine at the moment is subjected to table lookup through the established oil consumption map of the engine, and the economic area b with the lowest oil consumption rate is selected according to the required power at each moment _e (k) Obtaining the oil consumption value fuel (k, n, j) of the engine under a certain working condition, and respectively recording the battery power and the engine power at the moment as P _b (k,n,j)、P _ICE (k,n,j)；

When the system state is changed from SOC (k, n) to SOC (k +1, j), determining to obtain fuel consumption values fuel (k, n, j) according to the power distribution ratio, and referring a set consisting of all fuel consumption values fuel (k, n, j) at x (k) as a fuel consumption set fuel (k) at x (k) of the system state in a feasible region S, wherein the corresponding battery power and the engine power P are _b (k,n,j)、P _ICE The set of (k, n, j) is P _b (k)、P _ICE (k)；

And recording the oil consumption matrix as F = { fuel (k) |1 ≦ k ≦ N }.

7. The power distribution method of the hybrid system based on the open winding motor according to claim 6, wherein the step S5 comprises:

the optimization objective to minimize the cumulative fuel consumption of the driving cycle is expressed as:

when the system state is x (k), and k is more than or equal to 1 and less than or equal to N, the recursion equation is set as follows:

J _k ＝min[fuel(SOC(k),P _b (k),P _ICE (k))+J _k+1 (SOC(k))]in the formula J _k Representing the cumulative minimum oil consumption from the k step to the N step;

reversely pushing from the termination state to the initial state by a recursive calling mode, completing a traversal optimization searching process, and obtaining a power distribution track which enables oil consumption to be minimum;

the minimum oil consumption power distribution track sequence is recorded as:

U＝argmin[fuel(SOC(k),P _b (k),P _ICE (k))+J _k+1 (SOC(k))]。

8. the power distribution method of the hybrid power system based on the open winding motor as claimed in claim 6, wherein before the determination of the power distribution ratio of the motor, the preliminary screening of the discrete points at x (k + 1) is performed, and the method comprises the following steps:

maximum allowable discharge power of battery at x (k) of system state

The corresponding maximum discharge current of the battery is->

Setting the maximum discharge coefficient of the battery at x (k) under the system state

Set at point SOC (k, n) horizontal line l, I keeping SOC value constant _charmax Forms an angle theta with the horizontal line l ₁ ，I _discharmax Forms an angle theta with the horizontal line l ₂ Then, then

Forms an angle theta with the horizontal line l ₃ ＝k×θ ₂ The system state is a calculation range Δ SOC from a certain discrete point SOC (k, n) on x (k) to a discrete point SOC on x (k + 1) _max (k, n) is reduced to

Through preliminary screening, discrete points that are not reached by SOC (k, n) are excluded, and the points are determined

The power distribution ratio is determined, thereby reducing the amount of calculation and shortening the calculation time. />

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