CN117325719A - Voltage feedback battery preheating method of integrated electric drive system - Google Patents

Voltage feedback battery preheating method of integrated electric drive system Download PDF

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CN117325719A
CN117325719A CN202311325236.8A CN202311325236A CN117325719A CN 117325719 A CN117325719 A CN 117325719A CN 202311325236 A CN202311325236 A CN 202311325236A CN 117325719 A CN117325719 A CN 117325719A
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voltage
vector
time
battery
pwm
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李伟
石伟
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Hangzhou Weisheng Technology Co ltd
Jiaxing Research Institute of Zhejiang University
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Hangzhou Weisheng Technology Co ltd
Jiaxing Research Institute of Zhejiang University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K1/00—Arrangement or mounting of electrical propulsion units
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
    • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
    • B60L3/0046—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to electric energy storage systems, e.g. batteries or capacitors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/24—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries for controlling the temperature of batteries
    • B60L58/27—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries for controlling the temperature of batteries by heating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/615—Heating or keeping warm
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/62—Heating or cooling; Temperature control specially adapted for specific applications
    • H01M10/625—Vehicles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/63—Control systems
    • H01M10/633—Control systems characterised by algorithms, flow charts, software details or the like
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/654—Means for temperature control structurally associated with the cells located inside the innermost case of the cells, e.g. mandrels, electrodes or electrolytes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K1/00—Arrangement or mounting of electrical propulsion units
    • B60K2001/008—Arrangement or mounting of electrical propulsion units with means for heating the electrical propulsion units
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing

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Abstract

The invention relates to the field of battery heating, in particular to a voltage feedback battery preheating method of an integrated electric drive system, which comprises the steps of connecting a battery pack to a controller, inputting an upper limit control target value ub, max, o and a lower limit control target value ub, min of the battery pack to the controller, generating a 1-zero vector duty ratio d0 by a PI control module and transmitting the 1-zero vector duty ratio d0 to a PWM generator, calculating a PWM physical signal according to a motor electric angle theta by the PWM generator and transmitting the PWM physical signal to an inverter in the electric drive system, simultaneously generating a synchronous sampling signal and transmitting the synchronous sampling signal to a voltage peak-valley sampling module, sampling peak voltage ub, max and valley voltage ub, min of the battery pack after receiving the sampling synchronous signal by the voltage peak Gu Caiyang module, generating switching logic, and controlling the PI control module according to the switching logic by a switch; the voltage peak-valley sampling module and the PI control module are arranged, the voltage of the battery pack is controlled in the limit voltage range, the service life of the battery pack can be ensured, and the maximum battery heating rate is exerted.

Description

Voltage feedback battery preheating method of integrated electric drive system
Technical Field
The invention relates to the field of battery heating, in particular to a voltage feedback battery preheating method of an integrated electric drive system.
Background
Various performances of the power lithium ion battery for the vehicle decline sharply in a low-temperature environment: the charging is slow, and lithium is easy to separate out during high-current charging; the power density is reduced, and the discharge multiplying power is greatly reduced; accelerated decay of cycle life, etc.; the popularization of the pure electric vehicle in northern cold areas is severely restricted, and the low-temperature preheating is a feasible and effective technical scheme based on the current lithium ion battery technology. Compared with external heating, the alternating-current internal heating has the advantages of quick heating and no heating element, and in the prior art, the battery and the electric control circuit topology are required to be changed, so that certain difficulty exists in realization. In addition, aiming at the problem that lithium is easy to separate out in the charging and discharging process of the lithium ion battery in a low-temperature environment, a strategy for controlling polarization voltage is almost adopted. How to control the battery voltage in the preheating process of the integrated electric drive system, and ensuring the safety and the service life of the battery has no good solution, so it is necessary to provide a voltage feedback battery preheating method of the integrated electric drive system.
Disclosure of Invention
The invention aims to provide a voltage feedback battery preheating method of an integrated electric drive system, which can control the working voltage of a battery within a limit value thereof, can not damage the battery, and can also exert the maximum battery heating rate so as to solve the technical defects and the technical requirements which cannot be achieved in the prior art.
In order to achieve the above purpose, the present invention provides the following technical solutions: a voltage feedback battery preheating method of an integrated electro-drive system comprises the following steps:
1. connecting a preheating controller with a PI control module, switching logic, a voltage peak-to-valley sampling module and a PWM generator with a battery pack;
2. inputting an upper limit control target value ub, max, o and a lower limit control target value ub, min, o of the battery pack into the controller;
3. the PI control module generates a 1-zero vector duty ratio d0 and transmits the 1-zero vector duty ratio d0 to the PWM generator;
4. the PWM generator calculates PWM physical signals according to the motor electrical angle theta in the electric drive system and simultaneously generates synchronous sampling signals;
5. the PWM generator transmits PWM physical signals to an inverter in the electric drive system, and transmits synchronous sampling signals to a voltage peak Gu Caiyang module;
6. after receiving the sampling synchronization signal, the voltage peak Gu Caiyang module samples the peak voltage ub, max and the valley voltage ub, min of the battery pack, determines switching logic according to the peak voltage ub, max and the valley voltage ub, min, and finally controls a switch according to the switching logic;
7. the switch controls the PI control module according to the switching logic;
8. the inverter drives stator coils of the motor according to the PWM physical signal.
Preferably, in the fourth step, the step of calculating the PWM physical signal by the PWM generator according to the motor electrical angle θ in the electric driving system includes:
1) The PWM generator adds a zero vector circuit state into an effective vector circuit state and a dead zone vector circuit state, wherein the effective vector circuit state is composed of two basic vectors U4 and U6;
2) The PWM generator calculates the ratio of the action time T4 to the action time T6 of two basic vectors according to the electric angle theta of the motor;
3) The PWM generator then shows the dead zone vector action time Tx according to the proportionality constant C of the effective vector action total time (T4+T6) and the dead zone vector action time Tx, wherein the effective vector action total time is the sum of the two basic vector action times;
4) The PWM generator then shows zero vector acting time T0 according to the dead zone vector acting time Tx, the effective vector acting total time and the PWM period Ts;
5) The PWM generator again shows zero vector action time T0 according to the zero vector duty ratio and the PWM period Ts;
6) And respectively calculating dead zone vector acting time Tx, zero vector acting time T0 and two basic vector acting times according to the representation relation in the steps 2), 3), 4) and 5).
Preferably, the specific way of calculating the ratio of the two effective vector acting times T4 and T6 in the step 2) is as follows:
according to Park-cleke coordinate transformation formulaSubstituting ua=t4, ub= -T6, uc=0 into the above equation, and letting calculated uq=0, we can obtain
Preferably, the specific way to calculate the dead zone vector active time Tx, the zero vector active time T0 and the two base vector active times in steps 2) to 6) is:
from the proportionality constant C of the effective vector operation total time to the dead zone vector operation time Tx, it is possible to obtain:
from the overall control period Ts:
T s ＝T x +T 4 +T 6 +T 0 (3)
the overall control period Ts is determined by the motor control frequency H;
and the relation between the zero vector duty ratio d0 and the zero vector acting time T0 and the whole control period Ts is as follows:
and respectively calculating the values of dead zone vector acting time Tx, zero vector acting time T0 and two basic vector acting times according to the obtained relational expressions (1) - (4).
Preferably, the proportionality constant C is greater than 1.
Preferably, the zero vector active time is divided into two equal time slices, and the dead zone vector active time and the effective vector active time are inserted respectively.
Preferably, the sampling time of the peak voltage ub, max is before the dead zone vector ends, and the sampling time of the valley voltage ub, min is before the effective vector ends.
Preferably, the upper limit control target value ub, max, o is slightly smaller than the battery pack voltage upper limit value, and the lower limit control target value ub, min, o is slightly larger than the battery pack voltage lower limit value.
Preferably, the PI control module includes an upper limit PI and a lower limit PI, and the switch controls whether the zero vector duty ratio d0 input to the PWM generator is from the upper limit PI or from the lower limit PI according to the switching logic.
Preferably, the switching logic is: the voltage peak-valley sampling module monitors the feedback voltage peak value in real time firstly by using the lower limit PI control, if the voltage peak value ub, max is close to the upper limit, the feedback voltage peak value is switched into the upper limit PI control, after the upper limit PI control of the switching layer is switched, the voltage peak-valley sampling module starts to monitor the feedback voltage valley value, and if the voltage valley value ub, min is close to the lower limit, the feedback voltage peak value is switched back to the lower limit PI control.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the battery pack voltage control method, the voltage peak-valley sampling module and the PI control module are arranged, the upper limit PI and the lower limit PI are specifically arranged, the voltage of the battery pack can be controlled in the limit voltage range of the battery pack, the service life of the battery pack can be guaranteed, the maximum battery heating capacity is exerted, and the purpose of safe heating is achieved.
2. According to the method, the zero vector is inserted into the effective dead zone vector, the action time of the non-zero vector and the dead zone vector can be compressed, the amplitude of discharge current and charging current is reduced, the amplitude of battery voltage fluctuation is regulated, and the purpose of controlling the battery voltage is achieved.
3. The synchronous sampling signal is transmitted in the application, and the voltage peak value sampling time is fixed before the dead zone vector is ended, the voltage valley value sampling time is fixed before the effective vector is ended, so that voltage extreme value sampling can be carried out by avoiding voltage fluctuation of the battery in the repeated charge and discharge process, and the voltage extreme value point of the end part of the battery pack can be accurately measured, so that the accuracy of the application is ensured.
Drawings
FIG. 1 is a schematic diagram of an AC current control sequence according to the present invention;
FIG. 2 is a diagram of a warm-up strategy control architecture of the present invention;
FIG. 3 is a schematic diagram of the synchronization principle of the voltage sampling and PWM of the present invention;
FIG. 4 is a graph of battery voltage and duty cycle during heating of a fixed duty cycle control strategy in an experimental control;
FIG. 5 is a graph of battery voltage and duty cycle during heating of the present application in an experimental control;
FIG. 6 is a table comparing the ramp rate of the present application to a fixed duty cycle control strategy in an experimental control;
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 to 6 of the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1-6, embodiments of the present invention:
examples:
introducing a zero vector between the effective vector and the dead zone vector, and adjusting the voltage by adjusting the duty ratio of the zero vector in the whole control period, wherein the battery discharge current increases during the non-zero vector action; during zero vector operation, the battery current is zero, and the motor phase current decays rapidly; during dead zone vector operation, the battery current is reversed negative on the basis of the phase current to charge the battery. The addition of the zero vector compresses the time of the non-zero vector and the dead zone, so that the amplitudes of the discharging current and the charging current are reduced. The amplitude of the voltage fluctuation of the battery is directly regulated so as to achieve the effect of controlling the voltage.
As shown in fig. 1: assuming that the current motor rotor is located between the base vectors U4 and U6, the effective vectors in the present application are synthesized by the two base vectors U4 and U6, and the ratio of the time of action T4 and T6 of the U4 and U6 vectors is determined by the electrical angle of the current motor, with the principle of ensuring that the motor output torque is zero under the action of the synthesized vectors. When the upper rotor of the motor is in a static state, no phase difference exists between the voltage vector and the current vector, so that zero torque can be obtained as long as the voltage vector coincident with the d axis is given, the d axis is a synchronous rotation coordinate system adopted in vector control of the permanent magnet synchronous motor, the synchronous rotation coordinate system follows the motor rotor, the direction of the d axis is in the same direction as the magnetic pole of the permanent magnet of the motor stator, and according to a Park-cleke coordinate conversion formula:
substituting ua=t4, ub= -T6, uc=0 into the above equation, and letting the calculated uq=0, the ratio of T4 to T6 can be calculated from the current electrical angle θ of the motor, where the calculation equation is as follows:
where θ represents the current electrical angle of the motor rotor, as determined by the rotor position sensor measurements and the pole pair number. In order to generate positive and negative symmetry of the battery alternating current, the proportionality constant C of the non-zero vector and the dead zone vector is calibrated through a test, wherein the proportionality constant C is a constant larger than 1 and is taken as 1.6, namely:
as shown in fig. 1: the zero vector active time T0 is divided into two equal time slices, after insertion of the dead zone and the non-zero vector, respectively. The duration of the overall PWM period Ts is determined by the given motor control frequency, here the PWM frequency is set to the usual frequency of motor control, 10kHz, and therefore:
T s ＝T x +T 4 +T 6 +T 0 ＝0.1ms (3)
the three formulas are combined, and the zero vector duty ratio is given:
meanwhile, the current electrical angle theta of the motor is obtained, namely Tx, T4, T6 and T0 can be calculated, 6 paths of PWM waves containing the control signal d0 are compiled according to the current electrical angle theta, and the PWM generator can output signals.
As shown in fig. 2: the feedback control structure of the application comprises a controller and an electric drive system (a controlled object consisting of a battery pack, a motor and an inverter) in a dotted line frame, and in order to respectively control the upper limit battery voltage and the lower limit battery voltage, a PI control module is designed to be composed of two PI control loops: an upper limit PI and a lower limit PI;
the input variables of the controller are voltage target values ub, min, o and ub, max, o controlled by the upper limit voltage and the lower limit voltage of the battery pack, specifically, for a single lithium ion battery cell, the upper limit voltage and the lower limit voltage of the single lithium ion battery cell are multiplied by the serial number of the battery pack to obtain the upper limit value and the lower limit value of the battery pack voltage, and in order to ensure safety, ub, min, o is set to be slightly higher than the lower limit value of the battery pack terminal voltage, and ub, max, o is set to be slightly lower than the upper limit value of the battery pack terminal voltage;
and the 1-zero vector duty ratio d0 is defined as the output variable of the PI link, the range of the output variable is 0-1, and the value is transmitted to the PWM generator. Meanwhile, the PWM generator calculates according to formulas (1) - (4) according to the electric angle theta of the motor in the electric drive system to obtain 6 paths of PWM physical signals corresponding to the graph 1, outputs the PWM physical signals to an inverter in the electric drive system, and finally acts on a stator coil of the motor;
the PWM generator transmits a sampling synchronous signal to a voltage peak-to-valley sampling module, and the voltage peak-to-valley sampling module obtains voltage peaks ub and max and voltage valleys ub and min. The difference is respectively made between the voltage target values ub, min, o and ub, max and o controlled by the upper limit and the lower limit, namely ub, max-ub, max, o and ub, min-ub, min and o, and the result is input into an upper limit PI control module and a lower limit PI control module. Meanwhile, determining a switching logic according to the comparison result, and controlling a PI control module by a switch according to the switching logic, namely selecting upper limit PI control or lower limit PI control;
the switching of the upper limit PI and the lower limit PI is controlled by a switch connected after the output of the upper limit PI and the lower limit PI, the switch determines whether the signal input to the PWM generator at the current moment is from the upper limit PI or the lower limit PI, and the switching logic of the upper limit PI and the lower limit PI is as follows: firstly, using a lower limit PI control, sampling voltage peak values ub and max by a voltage peak Gu Caiyang module, and switching to the upper limit PI control if the voltage peak values ub and max are close to the upper limit; the voltage peak-valley sampling module collects voltage valley values ub and min at the same time, and if the voltage valley values ub and min are close to the lower limit, the voltage valley values ub and min are switched back to the lower limit PI control;
in order to prevent voltage from greatly overshooting, the output of the newly started PI control link is guaranteed to be zero at the initial moment and each switching moment, namely d0 is equal to 1, and the output is all zero vectors, so that the occurrence of excessively high or excessively low battery terminal voltage is avoided.
The specific battery heating process is as follows: the controller is set as a lower limit PI control by default at the initial moment, a battery heating process is started, when the valley voltage ub, min sampled by the voltage peak valley sampling module is lower than a lower limit target value ub, min and o, the lower limit PI controller increases d0 so as to reduce battery current and polarization voltage, thereby controlling battery pack end voltage above the allowable lower limit, otherwise, when the valley voltage ub, min sampled by the voltage peak valley sampling module is higher than the lower limit target value ub, min and o and is far lower than an upper limit target value ub, max and o, the lower limit PI controller decreases d0 so as to increase battery current and polarization voltage, thereby controlling battery pack end voltage to be close to the lower limit voltage, guaranteeing high-rate heating and controlling the voltage valley of the battery pack end to be stabilized near the target voltage valley; along with the rising of the battery temperature or in a higher state of the battery SOC, in the process of regulating and controlling the voltage valley, the voltage peak value ub, max sampled by the voltage peak valley sampling module also gradually rises and possibly approaches the upper limit voltage of the battery pack, when the voltage peak value ub, max is higher than the voltage target peak value ub, max, o, PI switching logic is triggered, the voltage is switched into upper limit PI control, the terminal voltage peak value of the battery pack is ensured not to exceed the upper limit, and in the upper limit PI control process, the valley voltage is monitored. That is, as the SOC decreases, if the voltage trough falls below the lower limit voltage, the control is switched back to the lower limit PI control to increase d0 and decrease the current, thereby controlling the voltage trough to the vicinity of the lower limit. By the control strategy, the peak-to-valley value of the battery pack terminal voltage can be controlled within the allowable upper and lower limits; the application sets up like this and can form alternating current in the battery package, and the temperature Tb of battery package can rise gradually simultaneously, if it is monitored that battery temperature Tb rises to the value that can start the vehicle, for example-10 ℃, stops above-mentioned all processes, the battery heating that ends.
The output anti-saturation strategy is designed in the PI controller, and the output quantity d0 is clamped between 0 and 1 in the specific application. To control the overshoot, the dynamic process is adjusted to resemble a progressive line of the over-damped condition. In order to improve the dynamic characteristics, the PI control period is defined as a PWM period Ts. Other parameters of the PI control link may be obtained based on experimental adjustments.
In the repeated charge and discharge process of the battery pack, the terminal voltage of the battery pack is necessarily fluctuated up and down. The relationship between the voltage fluctuation rule of the battery pack terminal and the PWM wave is shown in figure 1. At the moment of PWM switching, due to the action of the equivalent inductance in the bus and the battery, a rapid pulse disturbance appears in the voltage waveform of the battery terminal, and in order to accurately measure the extreme point of the voltage of the battery pack terminal, voltage sampling is performed before the action of the effective vector and the dead zone vector is finished so as to avoid the disturbance, which is the reason that the voltage peak sampling needs to be synchronous with PWM. Specifically, the voltage valley sampling time is set before the control signal of the A phase upper tube in the inverter is switched from high level to low level in each PWM period Ts, namely before the end of the effective vector; similarly, the voltage peak sampling instant is set before the dead band vector ends. The advance can be calibrated according to the test. These two moments are defined as sampling synchronization signals, which are transmitted by the PWM generator to the voltage peak-to-valley sampling module.
Experimental control:
in order to verify the feasibility and the advantages of the heating method, under the condition that the battery voltage is not exceeded, the constant-voltage control strategy is compared with the heating rate of the fixed duty ratio strategy, and the beneficial effects of the method are researched by a comparison test.
The specific battery is a 12-string battery pack, the upper and lower voltage limits are 30V and 50V respectively, and the SOC is 60%. The initial temperature and ambient temperature were both-30 ℃, and both tests stopped timing after the average battery temperature reached-10 ℃.
The first set of experiments employed a constant pressure control strategy: standing for 4 hours after the test is finished, and carrying out a second group of tests after the temperature of the battery is restored to the ambient temperature;
the second group of experiments adopts a fixed duty ratio strategy, the zero vector duty ratio is fixed to be 78.4%, the value is the duty ratio of the zero vector when the battery voltage reaches the lower limit at the temperature of minus 30 ℃, and the battery voltage is slowly raised along with the rise of the temperature, so that the battery voltage can be ensured not to exceed the limit in the preheating process only by outputting PWM waves according to the duty ratio.
As shown in fig. 4, under the fixed duty cycle strategy, the polarization voltage decreases as the battery temperature increases, and the minimum voltage gradually rises farther from the target value.
As can be seen from fig. 5, the constant voltage control strategy is capable of controlling the minimum voltage of the battery pack around the target value of 30.5V, with the effective vector duty cycle being gradually adjusted up during the test. Because of the low SOC, the battery voltage does not exceed the upper limit throughout the process.
As shown in fig. 6, the temperature curves corresponding to the two sets of tests and the heating time are shown, and it is clear from the graph that the temperature rising rate of the fixed duty ratio strategy gradually decreases, because as the surface temperature of the battery increases, the surface heat dissipation rate increases due to the corresponding increase of the temperature difference between the surface and the environment, and meanwhile, the internal resistance of the battery decreases due to the increase of the temperature, so that the internal heat generation rate of the battery decreases. Eventually, the temperature rise rate gradually decreases. Similarly, if the constant voltage control strategy provided by the patent is adopted, the battery voltage can be controlled within the allowable limit value in the whole heating process, and the self-heating capacity of the battery can be fully exerted. Therefore, as the temperature rises, the rate of increase of the self-heating power inside the battery is larger than the rate of increase of the surface heat dissipation rate, which is shown as the heating rate is in an ascending trend, and finally, the heating rate of the whole heating process is effectively improved.
While the fundamental and principal features of the invention and advantages of the invention have been shown and described, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to specific embodiments, and that the embodiments described in the examples can be combined as appropriate to form other embodiments that will be understood by those skilled in the art.

Claims (10)

1. The voltage feedback battery preheating method of the integrated electric drive system is characterized by comprising the following steps of:
1. connecting a preheating controller with a PI control module, switching logic, a voltage peak-to-valley sampling module and a PWM generator with a battery pack;
2. inputting an upper limit control target value ub, max, o and a lower limit control target value ub, min, o of the battery pack into the controller;
3. the PI control module generates a 1-zero vector duty ratio d0 and transmits the 1-zero vector duty ratio d0 to the PWM generator;
4. the PWM generator calculates PWM physical signals according to the motor electrical angle theta in the electric drive system and simultaneously generates synchronous sampling signals;
5. the PWM generator transmits PWM physical signals to an inverter in the electric drive system, and transmits synchronous sampling signals to a voltage peak Gu Caiyang module;
6. after receiving the sampling synchronization signal, the voltage peak Gu Caiyang module samples the peak voltage ub, max and the valley voltage ub, min of the battery pack, and then determines switching logic according to the peak voltage ub, max and the valley voltage ub, min;
7. the switch controls the PI control module according to the switching logic;
8. the inverter drives stator coils of the motor according to the PWM physical signal.
2. The method for preheating a voltage feedback battery of an integrated electro-mechanical driving system according to claim 1, wherein in the fourth step, the PWM generator calculates the PWM physical signal according to the motor electrical angle θ in the electro-mechanical driving system, which comprises the steps of:
1) The PWM generator adds a zero vector circuit state into an effective vector circuit state and a dead zone vector circuit state, wherein the effective vector circuit state is composed of two basic vectors U4 and U6;
2) The PWM generator calculates the ratio of the action time T4 to the action time T6 of two basic vectors according to the electric angle theta of the motor;
3) The PWM generator then shows dead zone vector action time Tx according to a proportionality constant C of the effective vector action total time and the dead zone vector action time Tx, wherein the effective vector action total time is the sum of two basic vector action times;
4) The PWM generator then shows zero vector acting time T0 according to the dead zone vector acting time Tx, the effective vector acting total time and the PWM period Ts;
5) The PWM generator again shows zero vector action time T0 according to the zero vector duty ratio d0 and the PWM period Ts;
6) And respectively calculating dead zone vector acting time Tx, zero vector acting time T0 and two basic vector acting times according to the representation relation in the steps 2), 3), 4) and 5).
3. The method for preheating a voltage feedback battery of an integrated electro-drive system according to claim 2, wherein the specific manner of calculating the ratio of T4 to T6 between the two effective vector actions in step 2) is as follows:
according to Park-cleke coordinate transformation formulaSubstituting ua=t4, ub= -T6, uc=0 into the above equation, and letting calculated uq=0, we can obtain
4. A method for preheating a voltage feedback battery of an integrated electro-drive system according to claim 3, wherein the dead zone vector on time Tx, the zero vector on time T0, and the two base vector on times are calculated in steps 2) to 6):
from the proportionality constant C of the effective vector operation total time to the dead zone vector operation time Tx, it is possible to obtain:
from the PWM period Ts:
T s ＝T x +T 4 +T 6 +T 0 (3)，
the PWM period Ts is determined by the motor control frequency H;
and the relation between the zero vector duty ratio d0 and the zero vector acting time T0 and PWM period Ts is as follows:
and respectively calculating the values of dead zone vector acting time Tx, zero vector acting time T0 and two basic vector acting times according to the obtained relational expressions (1) - (4).
5. The method of claim 4, wherein the proportionality constant C is greater than 1.
6. A method of preheating a voltage feedback battery of an integrated electro-drive system as claimed in claim 1, 2, 3, 4 or 5, wherein the zero vector active time is divided into two equal time slices inserted after the dead zone vector active time and the active vector active time, respectively.
7. The method for preheating a voltage feedback battery of an integrated electro-drive system according to claim 6, wherein the sampling time of the peak voltage ub, max is before the dead zone vector ends, and the sampling time of the valley voltage ub, min is before the effective vector ends.
8. The method of claim 7, wherein the upper control target value ub, max, o is slightly smaller than the upper limit value of the battery pack voltage, and the lower control target value ub, min, o is slightly larger than the lower limit value of the battery pack voltage.
9. A method of preheating a voltage fed back battery of an integrated electro-drive system as claimed in claim 1, 2, 3, 4, 5, 7 or 8, wherein the PI control module comprises an upper limit PI and a lower limit PI, and the switch controls whether the 1-zero vector duty cycle d0 input to the PWM generator is from the upper limit PI or from the lower limit PI according to the switching logic.
10. The method of claim 9, wherein the switching logic is configured to: the feedback voltage peak value is monitored in real time by the voltage peak-valley sampling module through the lower limit PI control, if the voltage peak value ub, max is close to the upper limit control target value ub, max, o, the feedback voltage peak value is switched into the upper limit PI control, after the feedback voltage peak value is switched into the upper limit PI control, the voltage peak-valley sampling module starts to monitor the feedback voltage valley value, and if the voltage valley value ub, min is close to the lower limit control target value ub, min, o, the feedback voltage peak value is switched back to the lower limit PI control.
CN202311325236.8A 2023-10-13 2023-10-13 Voltage feedback battery preheating method of integrated electric drive system Pending CN117325719A (en)

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