CN114537226A

CN114537226A - Power assembly circuit of electric automobile and power battery heating method

Info

Publication number: CN114537226A
Application number: CN202210216059.9A
Authority: CN
Inventors: 李一粟; 海栋
Original assignee: Leadrive Technology Shanghai Co Ltd
Current assignee: Leadrive Technology Shanghai Co Ltd
Priority date: 2022-03-07
Filing date: 2022-03-07
Publication date: 2022-05-27
Anticipated expiration: 2042-03-07
Also published as: CN114537226B

Abstract

The invention provides a power assembly circuit of an electric automobile and a power battery heating method, wherein the power assembly circuit comprises: the power supply is arranged on the power assembly circuit; the motor controller is connected in parallel with two ends of the power supply and comprises a first phase, a second phase and a third phase which form a three-phase circuit; the LC circuit is connected between the power supply and the motor controller in parallel; the motor comprises a first winding, a second winding and a third winding which form a three-phase winding, wherein the first winding, the second winding and the third winding are respectively connected with a first phase, a second phase and a third phase in parallel; the motor controller detects the resonant frequency of the LC circuit and modulates the carrier frequencies of the first, second, and third phases to be equal to the resonant frequency, so that the inverter supplies the maximum input current to the power supply to maximize the heating effect of the power supply. After the technical scheme is adopted, the problems of long consumption time and large energy loss under the condition of low-temperature heating of the power battery of the electric automobile can be solved. Meanwhile, the problem that other pulse heating functions cannot heat the battery in the driving process can be solved.

Description

Power assembly circuit of electric automobile and power battery heating method

Technical Field

The invention relates to the field of new energy vehicle control, in particular to a power assembly circuit of an electric automobile and a power battery heating method.

Background

With the rapid development of electric vehicles, the main problems to be solved are the endurance mileage and the charging speed of the user. When the electric automobile is switched from the starting state to the driving state, if the battery is in a low-temperature state, the output voltage, the maximum allowable power, the driving range and the service life of the battery are greatly influenced. After the temperature of the battery is raised to the normal working temperature, the battery can normally run. Therefore, the battery heating device has the function of heating the battery, so that the battery can work at a proper temperature, the battery can have proper performance under various working conditions, and the service life of the battery is prolonged.

In the conventional scheme, external devices such as a PTC are generally used to heat the battery. However, this solution increases the hardware cost on the one hand and is not very efficient in heating on the other hand, and much heat is dissipated in the air due to the thermal resistance of the heat conduction path. Other newer schemes charge and discharge the motor by controlling an inverter, thereby generating a pulse current to heat the battery. However, the solutions have the disadvantages that the heating efficiency is not high enough, and the solutions can only be used in a parking state.

Therefore, a new power assembly circuit and a new power battery heating method for an electric vehicle are needed, which can realize the most efficient heating of the power battery.

Disclosure of Invention

In order to overcome the technical defects, the invention aims to provide a power assembly circuit of an electric vehicle and a power battery heating method, which can solve the problems of long consumption time and large energy loss under the condition of low-temperature heating of the power battery of the electric vehicle.

The invention discloses a power assembly circuit of an electric automobile, which is arranged in the electric automobile, and comprises:

the power supply is arranged on the power assembly circuit;

the motor controller is connected in parallel with two ends of the power supply and comprises a first phase, a second phase and a third phase which form a three-phase circuit;

the LC circuit is connected between the power supply and the motor controller in parallel;

the motor comprises a first winding, a second winding and a third winding which form a three-phase winding, wherein the first winding, the second winding and the third winding are respectively connected with a first phase, a second phase and a third phase in parallel, and the first winding, the second winding and the third winding are connected with the first phase, the second phase and the third phase in parallel, wherein

The first phase comprises a switch tube S1 and a switch tube S2 which are connected in series and are connected to a power assembly circuit in parallel;

the second phase comprises a switch tube S3 and a switch tube S4 which are connected in series and are connected to the power assembly circuit in parallel;

the third phase comprises a switch tube S5 and a switch tube S6 which are connected in series and are connected to the power assembly circuit in parallel;

one end of the first winding is connected between the switch tube S1 and the switch tube S2;

one end of the second winding is connected between the switch tube S3 and the switch tube S4;

one end of the third winding is connected between the switch tube S5 and the switch tube S6;

the motor controller detects the resonant frequency of the LC circuit and modulates the carrier frequencies of the first phase, the second phase and the third phase to be equal to the resonant frequency, so that an inverter formed by the first winding, the second winding and the third winding transmits the maximum input current to the power supply, and the heating effect of the power supply is maximized.

Preferably, the motor controller draws or measures a frequency-gain curve graph of the LC circuit, and extracts a frequency corresponding to a maximum gain in the frequency-gain curve graph as a resonant frequency of the LC circuit;

the motor controller matches the carrier frequency with the resonant frequency so that the effective values of the power supply current of the power supply, the bus current of the LC circuit, and the capacitance current are consistent.

Preferably, the motor controller calculates a theoretical resonant frequency from the capacitance data and the inductance data of the LC circuit;

the motor controller measures the temperature rise value of the power supply or the bus current effective value of the LC circuit, and iterates repeatedly on two sides of the theoretical resonant frequency until the temperature rise value of the power supply or the bus current effective value of the LC circuit is maximum;

and the motor controller records the maximum frequency of the temperature rise value of the power supply or the bus current effective value of the LC circuit as the actual resonance frequency of the LC circuit.

Preferably, the motor controller controls carrier inversion of any one of the first phase, the second phase, and the third phase.

Preferably, the waveform of the output current of the motor is one or more of a square wave, a triangular wave or a sine wave;

the motor controller controls vectors and directions of first current, second current and third current on a first phase, a second phase and a third phase to be coincided with the direction of a d axis of the current angle through dq transformation according to the current angle of the motor;

and the motor controller calculates the maximum value of the first current, the second current and the third current, and the carrier wave corresponding to the maximum current is reversed.

Preferably, the motor controller calculates equivalent q-axis current and d-axis current of the first current, the second current and the third current of the first phase, the second phase and the third phase based on SVPWM/SPWM algorithm;

when the electric automobile is in a driving state, one of the first current, the second current and the third current is added to the bus current of the LC circuit by the equivalent d-axis current after the carrier wave is reversed.

Preferably, the motor controller calibrates the carrier images of the first phase, the second phase and the third phase of the motor in the circumferential range in an off-line environment;

determining a carrier reversal strategy based on the amplitudes of a first phase carrier, a second phase carrier and a third phase carrier of a carrier image, wherein the carrier reversal strategy comprises the following steps:

the motor adjusts the carrier reverse phases in the first phase, the second phase and the third phase every 60 degrees of deflection, and the carrier reverse sequence of the first phase reverse, the third phase reverse, the second phase reverse, the first phase reverse, the third phase reverse and the second phase reverse is maintained in the circumferential range.

The invention also discloses a power battery heating method of the electric automobile, which is characterized by comprising the following steps of:

configuring a powertrain circuit, the powertrain circuit comprising: the power supply is arranged on the power assembly circuit; the motor controller is connected in parallel with two ends of the power supply and comprises a first phase, a second phase and a third phase which form a three-phase circuit; the LC resonance circuit is connected between a power supply and the motor controller in parallel, wherein L of the LC resonance circuit is generally composed of a cable parasitic inductance L connected with the motor controller and a battery, and C is mainly a bus capacitor of the motor controller; the motor comprises a first winding, a second winding and a third winding which form three-phase windings, wherein the first winding, the second winding and the third winding are respectively connected with a first phase, a second phase and a third phase in parallel, the first phase comprises a switch tube S1 and a switch tube S2 which are connected in series and connected to a power assembly circuit in parallel; the second phase comprises a switch tube S3 and a switch tube S4 which are connected in series and are connected to the power assembly circuit in parallel; the third phase comprises a switch tube S5 and a switch tube S6 which are connected in series and are connected to the power assembly circuit in parallel; one end of the first winding is connected between the switch tube S1 and the switch tube S2; one end of the second winding is connected between the switch tube S3 and the switch tube S4; one end of the third winding is connected between the switch tube S5 and the switch tube S6;

the motor controller detects the resonant frequency of the LC circuit and modulates the carrier frequencies of the first, second, and third phases to be equal to the resonant frequency, so that the motor delivers a maximum input current to the power supply to maximize the heating effect of the power supply.

Preferably, the method further comprises the following steps:

the motor controller controls the carrier wave reversal of any one of the first phase, the second phase and the third phase.

Preferably, the method further comprises the following steps:

the motor controller calculates q-axis current and d-axis current equivalent to first current, second current and third current of a first phase, a second phase and a third phase based on an SVPWM/SPWM algorithm;

After the technical scheme is adopted, compared with the prior art, the method has the following beneficial effects:

1. the efficient heating of the power battery is completed under the modulation of the optimal carrier frequency;

2. the problem that extra equipment and devices are needed in a heating circuit of a power battery of the electric automobile is solved, and the cost is reduced;

3. the effective value of the current of the motor is transmitted to the bus through carrier interleaving, and then transmitted to the power supply side, so that the high-frequency heating of the power battery is realized;

4. the function of heating by using the motor winding is not interfered with the function of normal running of the whole vehicle, and the heating function of the whole vehicle in the running state is realized.

Drawings

FIG. 1 is a schematic circuit topology of a powertrain circuit of an electric vehicle in accordance with a preferred embodiment of the present invention;

FIG. 2 is a diagram illustrating three phase current waveforms of a motor when a motor controller controls DC of the motor according to a preferred embodiment of the present invention;

FIG. 3 is a waveform diagram of the power supply current, the bus current and the capacitor current when the motor controller controls the DC of the motor according to a preferred embodiment of the present invention

FIG. 4 is a frequency-gain plot of an LC circuit in accordance with a preferred embodiment of the present invention;

FIG. 5 is a vector sum schematic of first, second and third currents on first, second and third phases in accordance with a first embodiment of the present invention;

fig. 6 is a vector sum diagram of first, second and third currents in first, second and third phases in accordance with a second embodiment of the present invention.

Detailed Description

The advantages of the invention are further illustrated in the following description of specific embodiments in conjunction with the accompanying drawings.

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

The terminology used in the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

It is to be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish one type of information from another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present disclosure. The word "if" as used herein may be interpreted as "at … …" or "when … …" or "in response to a determination", depending on the context.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.

In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, a communication between two elements, a direct connection, or an indirect connection via an intermediate medium, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.

In the following description, suffixes such as "module", "component", or "unit" used to denote elements are used only for facilitating the explanation of the present invention, and have no specific meaning in themselves. Thus, "module" and "component" may be used in a mixture.

Referring to fig. 1, a schematic circuit topology of a powertrain circuit of an electric vehicle according to a preferred embodiment of the present invention is shown, in which the powertrain circuit is disposed in the electric vehicle, and specifically includes:

-a power supply

A power source, such as a battery, a battery pack, etc., is a device disposed in an electric vehicle that provides an electrical power output for the electric vehicle. When the power in the power supply is depleted, it needs to be charged. Thus, the power source is disposed on the powertrain circuit and current is input to the power source by other devices on the powertrain circuit.

-a motor controller

The motor controller is usually a neural center for connecting the motor and the battery, is used for adjusting and calibrating various performances of the whole electric automobile, plays a role in ensuring basic safety and accurate control of the automobile, and can also enable the battery and the motor to exert sufficient strength. In the present embodiment, the motor controller is different from the original function (or is based on the original function), and a configuration for charging the power supply is added, that is, the motor controller in the present embodiment is used for controlling the motor and also for controlling the charging of the power supply. Specifically, the motor controller is connected in parallel across the power supply, and has therein a first phase, a second phase, and a third phase forming a three-phase circuit, that is, U, V, W phase which is commonly understood (correspondence of the first phase, the second phase, and the third phase to U, V, W phase is not limited in the present invention, and any one phase may be regarded as the first phase, and so on). Likewise, in this embodiment, the three-phase circuit, in addition to being used for control of the motor, will also affect the state of charge of the powertrain circuit to the power source.

-LC circuit

In order to filter the bus-side current (bus current) of the power supply, an LC circuit is connected in parallel between the power supply and the motor controller. The LC circuit comprises an inductor L1 and a capacitor C1, wherein the inductor L1 is connected with one end of a power supply, and the capacitor C1 is connected in parallel with two ends of the power supply and is positioned behind the inductor L1. It should be emphasized that the L1 of the present invention is mainly composed of the parasitic inductance of the wiring harness from the battery to the inverter, and generally the inductance L1 is not increased in the prior art (this increases the circuit load, and on the contrary, the cable structure is adopted in the prior art). Preferably, the reactance of C1 can be regarded as a capacitor equivalent resistance ESR, and forms a second-order circuit together with the inductor L1, the capacitor C1 and the internal resistance of the power supply.

-an electric machine

The motor is equipment for converting electric energy into mechanical energy in the electric automobile. In this embodiment, the motor includes a first winding, a second winding, and a third winding that form a three-phase winding, and the first winding, the second winding, and the third winding are respectively connected in parallel with the first phase, the second phase, and the third phase to complete the basic control of the motor controller on the motor.

After the configuration is adopted, when the motor is started, the three-phase winding of the motor forms a three-phase inductance, the first phase, the second phase and the third phase are used as the switching bridge arm of the boosting power assembly circuit, and the generated electric energy is input into the power supply through the switching bridge arm, so that the power supply is heated.

Furthermore, the specific components of the powertrain circuit are configured as follows: the first phase comprises a switch tube S1 and a switch tube S2 which are connected in series and are connected to a power assembly circuit in parallel; the second phase comprises a switch tube S3 and a switch tube S4 which are connected in series and are connected to the power assembly circuit in parallel; the third phase comprises a switch tube S5 and a switch tube S6 which are connected in series and are connected to the power assembly circuit in parallel; one end of the first winding is connected between the switching tube S1 and the switching tube S2; one end of the second winding is connected between the switch tube S3 and the switch tube S4; one end of the third winding is connected between the switch tube S5 and the switch tube S6.

In order to improve the heating (temperature rising) effect of the motor on the power supply to the maximum efficiency, that is, make the bus current of the power supply as large as possible under the condition of the same motor input current, in this embodiment, the motor controller detects the resonant frequency of the LC circuit, and modulates the carrier frequencies of the first phase, the second phase and the third phase to be equal to the resonant frequency. It can be understood that, when the LC circuit is in the resonance state, referring to fig. 2 and 3, the effective value of the bus current is consistent with the effective value of the three-phase current, and the gain of the LC circuit is in the maximum state, so that the bus current, that is, the effective value of the power branch current, is significantly increased, thereby increasing the input current value to the power supply.

It will be appreciated by those skilled in the art that the LC circuit generally has little effect on the circuit in the powertrain circuit, and that the reduced input current should be minimal, if not at the resonant frequency coinciding with the carrier frequency. However, after experimental verification, it is found that when the resonant frequency is consistent with the carrier frequency, the output voltage increases by about 20%, which is a non-negligible change, so that the bus current also increases by 20% correspondingly. The traditional curing concept can be broken through by the result, the resonance control of the LC circuit can also improve the heating effect of the power supply, and the heating effect is the optimal solution in all existing heating schemes.

In a preferred embodiment, referring to fig. 4, to accurately determine the resonant frequency of the LC circuit, the motor controller will plot or measure (off-line) a frequency-gain curve plot of the LC circuit at each frequency, and extract the frequency corresponding to the maximum gain in the frequency-gain curve plot based on the fitted curve. It can be understood that the frequency-gain curve graph is drawn, and the magnitude of the bus current can be detected by the motor controller in real time to determine the gain effect of the output current of the motor on the bus current at each frequency. Once the resonant frequency of the LC circuit is obtained, the motor controller controls the switching frequencies of the first phase, the second phase, and the third phase, so that the carrier frequency of the motor is modulated and matched with the resonant frequency, and the effective values of the power supply current of the power supply, the bus current of the LC circuit, and the capacitor current are consistent.

Further, to more accurately determine the resonant frequency of the LC circuit, the motor controller will calculate the theoretical resonant frequency based on the capacitance data of the capacitance C1 of the LC circuit and the inductance data of the inductance L1. For example, the calculation formula that can be used is:

preferably, a more accurate resonance frequency may be calculated considering the internal resistance of the battery and the equivalent resistance of the cable. At the theoretical resonant frequencyOn both sides of the frequency, the gain values at other frequencies can be repeatedly calculated (or the temperature rise value of the power supply or the bus current effective value of the LC circuit can be directly detected) to determine that the theoretical resonant frequency is the true resonant frequency, and if the temperature rise value of the power supply is greater than the temperature rise value of the power supply at the theoretical resonant frequency when the theoretical resonant frequency is not the theoretical resonant frequency, the frequency at which the temperature rise value of the power supply or the bus current effective value of the LC circuit is the maximum at each frequency is recorded as the actual resonant frequency of the LC circuit.

In a further preferred embodiment, to further improve the heating efficiency of the power supply, the motor controller further reverses the carrier wave controlling any one of the first phase, the second phase, and the third phase. After the electric vehicle is started, the first phase, the second phase and the third phase have a first current, a second current and a third current. To achieve a small influence on the operating state of the electric machine, for example, typically 0 torque control, the vectorial sum of the first, second and third currents is controlled to 0. In this embodiment, however, the carrier of a certain phase current will be chosen to be reversed such that the vector sum is not 0. After the carrier wave of a certain phase current is reversed, the time for simultaneously conducting three upper tubes or three lower tubes of the motor is effectively shortened, the effective value of the output current of the motor is transmitted to the bus side as far as possible, and then the output current is transmitted to the battery branch, so that the high-frequency heating of the power battery is realized.

It is again emphasized that the carrier reversal strategy is often considered in the art to have no effect or enhanced effect on battery heating. Even the prevailing idea is that once carrier inversion is performed, the thermal stress on the bus capacitance has a negative effect. Under the working condition, the heating effect of the battery can be effectively improved, and the prejudice of the industry is overcome.

Further, the waveform of the output current of the motor may be one or more of a square wave, a triangular wave, or a sine wave. It should be noted that, in the technical field, when an electric vehicle is started, it is a common practice that a motor controller controls switching frequencies of a first phase, a second phase and a third phase, so that a power supply can be charged only when an alternating current is output by a motor. That is, the waveform of the output current of the motor is a sine wave. However, when the carrier wave reverse heating mode is adopted, the output current form of the motor, such as direct current of square wave and alternating current of triangular wave, can be ignored. At any switching frequency, an increase in heating effect can be achieved. Meanwhile, in order to still realize the 0-torque control of the motor, in this embodiment, the motor controller will acquire the current angle of the motor and control the vectors and directions of the first current, the second current and the third current on the first phase, the second phase and the third phase to coincide with the d-axis direction of the current angle through dq transformation. The dq transformation is referred to in fig. 5, which means that the vector sum of the first current, the second current and the third current is converted into the vector sum of the currents on the d axis and the q axis at the current angle. And to realize 0 torque, the current magnitude on the d-axis should be the vector magnitude of the first current, the second current and the third current (in this case, the q-axis current is 0). Under the control requirement, the motor controller calculates the maximum value of the first current, the second current and the third current, and selects the phase corresponding to the maximum value of the first current, the second current and the third current in the carrier direction in the opposite direction. Therefore, the current value of the carrier wave reversal is the largest, and the heating effect on the power battery is maximized.

In the above embodiment, for the specific implementation of carrier inversion, one of the carriers can be inverted using SVPWM/SPWM control strategy. The SPWM is called as Sinussoidal PWM (Sinusoidal pulse width modulation), and the basic principle of the SPWM is the area equivalent principle, namely, when narrow pulses with equal impulse but different shapes are added to links with inertia, the effect is basically the same. In other words, the integration of corresponding time is equal (the area is equal) through a series of narrow pulse signals with different shapes, and the final effect is the same. Therefore, SPWM inputs a pulse sequence of equal amplitude to equalize a sine wave, so that the time width of the output high pulse varies substantially sinusoidally. SVPWM (space voltage vector PWM) is a pulse width modulated wave generated by a specific switching pattern consisting of six power switching elements of a three-phase power inverter, and is capable of making an output current waveform as close to an ideal sinusoidal waveform as possible. The space voltage vector PWM is different from the traditional sine PWM, and the method is based on the overall effect of three-phase output voltage and aims to make the motor obtain an ideal circular flux linkage track. Compared with the SPWM, the SVPWM technology has the advantages that harmonic components of winding current waveforms are small, so that motor torque pulsation is reduced, a rotating magnetic field is more approximate to a circle, the utilization rate of direct-current bus voltage is greatly improved, and digitization is easier to realize.

It is understood that, in the above embodiments, the electric vehicle is started, but is not yet running. However, it is understood that the user has a habit of using the electric vehicle that the electric vehicle is in a running state by pressing the accelerator after getting on and starting. Preferably or alternatively, therefore, under the above conditions, the motor controller will calculate equivalent q-axis and d-axis currents for the first, second and third currents of the first, second and third phases based on the SVPWM/SPWM algorithm, for example, reference currents in d-axis and q-axis directions are given, and based on an Iq regulator (a regulating module for q-axis current) and an Id regulator (a regulating module for d-axis current), according to the d-axis, q-axis and three-phase transformation rules (or the d-axis, q-axis and fixed alpha-axis, beta-axis transformation rules), after the carrier interleaving (namely when the forward carrier is maximum, the reverse carrier is minimum), the carriers are mutually orthogonal or SVPWM control, the motor is controlled to calculate q-axis current and d-axis current equivalent to the first current, the second current and the third current of the first phase, the second phase and the third phase (see fig. 6). Wherein the q-axis current is used for strengthening the motor torque and is generally called active current, the d-axis current is used for weakening magnetic flux and is generally called reactive current, and the reactive current is transmitted to the bus side to heat the power battery. Specifically, when the electric automobile is in a driving state, the motor controller controls q-axis current and d-axis current of the motor based on an SVPWM/SPWM algorithm, so that the motor works in a normal running state. After the carrier wave of one phase is controlled to be reversed by the rear fixing, the reactive current effective value of the motor is transmitted to the power battery, namely, the equivalent d-axis current after the carrier wave of the first current, the second current and the third current is reversed is supplemented to the bus current of the LC circuit. Further, if the d-axis current is increased at a high power factor, the effective value of the current on the power battery side can be increased.

In a further preferred embodiment, the phase selection of the carrier direction is not fixed, but is adjusted in time according to the angle of the motor. It will be appreciated that in the above embodiment, the phase with the largest current value is selected for the carrier reversal, and the phase with the largest current value is always changed during the rotation of the rotor of the motor, so that the phase of the carrier reversal is also controlled in a variable manner. The specific implementation is that, in an offline environment (for example, in an experimental environment), the carrier images of the first phase, the second phase and the third phase of the motor are calibrated in a circumferential range (every 360 °), and it can be known from the carrier images that the amplitudes of the current signals of the first phase, the second phase and the third phase are alternately maximum, for example, when the absolute value of the first current of the first phase is maximum, the switching conditions of the second phase and the third phase should be opposite as much as possible, so that the carrier of the first phase needs to be reversed at this time. Meanwhile, as can be seen from the carrier image, in each period, 6 times of phase transformation of the maximum current value occurs, and the phase transformation is respectively performed according to the sequence of the first phase, the third phase and the second phase, so that a carrier reversal strategy is determined based on the amplitudes of the first phase carrier, the second phase carrier and the third phase carrier of the carrier image, and the carrier reversal strategy includes: the motor adjusts the carrier reverse phases in the first phase, the second phase and the third phase every 60 degrees of deflection, and the carrier reverse sequence of the first phase reverse, the third phase reverse, the second phase reverse, the first phase reverse, the third phase reverse and the second phase reverse is maintained in the circumferential range. That is, each time only one phase is carrier-reversed and then the carrier of the next phase is reversed, the phase of the previous carrier reversal is maintained. It should be noted that the three-phase carrier image with the carrier inverted in the reverse direction is based on three-phase current signals, and modulated wave signals cannot be used. Because a change in power factor causes a shift in the current phase from the voltage phase (modulation wave phase). The use of three-phase current signals can ensure that the strategy is effective under different power factors. And when the carrier wave is reversed every time, the THD of the output current of the motor is increased, and the carrier wave reversal frequency needs to be reduced as far as possible. As described above, there are six carrier reversals per fundamental period, and the loop reversal, which ensures that only one phase carrier is flipped at a time, then 6 carrier reversals will be performed in the fundamental period.

The invention also discloses a power battery heating method of the electric automobile, which comprises the following steps: configuring a powertrain circuit, the powertrain circuit comprising: the power supply is arranged on the power assembly circuit; the motor controller is connected in parallel with two ends of the power supply and comprises a first phase, a second phase and a third phase which form a three-phase circuit; the LC circuit is connected between the power supply and the motor controller in parallel; the motor comprises a first winding, a second winding and a third winding which form three-phase windings, wherein the first winding, the second winding and the third winding are respectively connected with a first phase, a second phase and a third phase in parallel, the first phase comprises a switch tube S1 and a switch tube S2 which are connected in series and connected to a power assembly circuit in parallel; the second phase comprises a switch tube S3 and a switch tube S4 which are connected in series and are connected to the power assembly circuit in parallel; the third phase comprises a switch tube S5 and a switch tube S6 which are connected in series and are connected to the power assembly circuit in parallel; one end of the first winding is connected between the switch tube S1 and the switch tube S2; one end of the second winding is connected between the switch tube S3 and the switch tube S4; one end of the third winding is connected between the switch tube S5 and the switch tube S6; the motor controller detects the resonant frequency of the LC circuit and modulates the carrier frequencies of the first phase, the second phase and the third phase to be equal to the resonant frequency, so that an inverter formed by the first winding, the second winding and the third winding transmits the maximum input current to the power supply, and the heating effect of the power supply is maximized.

Preferably or optionally, further comprising the steps of: the motor controller controls the carrier wave reversal of any one of the first phase, the second phase and the third phase.

Preferably or optionally, further comprising the steps of: the motor controller calculates q-axis current and d-axis current equivalent to first current, second current and third current of a first phase, a second phase and a third phase based on an SVPWM/SPWM algorithm; when the electric automobile is in a driving state, one of the first current, the second current and the third current is added to the bus current of the LC circuit by the equivalent d-axis current after the carrier wave is reversed.

It should be noted that the embodiments of the present invention have been described in terms of preferred embodiments, and not by way of limitation, and that those skilled in the art can make modifications and variations of the embodiments described above without departing from the spirit of the invention.

Claims

1. The utility model provides an electric automobile's power assembly circuit, locates in electric automobile, its characterized in that, power assembly circuit includes:

the power supply is arranged on the power assembly circuit;

the motor comprises a first winding, a second winding and a third winding which form a three-phase winding, wherein the first winding, the second winding and the third winding are respectively connected with the first phase, the second phase and the third phase in parallel, and the three-phase winding is connected with the first phase, the second phase and the third phase in parallel, wherein

2. The powertrain circuit of claim 1,

the motor controller draws or measures a frequency-gain curve graph of the LC circuit, and extracts the frequency corresponding to the maximum gain in the frequency-gain curve graph as the resonant frequency of the LC circuit;

the motor controller matches a carrier frequency with the resonance frequency so that effective values of a power supply current of the power supply, a bus current of the LC circuit, and a capacitance current are consistent.

3. The powertrain circuit of claim 2,

the motor controller calculates theoretical resonant frequency according to capacitance data and inductance data of the LC circuit;

4. The powertrain circuit of claim 1,

5. The powertrain circuit of claim 4,

the waveform of the output current of the motor is one or more of square wave, triangular wave or sine wave;

the motor controller controls vectors and directions of first current, second current and third current on a first phase, a second phase and a third phase to be coincided with a d-axis direction of the current angle through dq transformation according to the current angle of the motor;

6. The powertrain circuit of claim 4,

when the electric automobile is in a running state, one of the first current, the second current and the third current is subjected to carrier reversal, and then equivalent d-axis current is supplemented to the bus current of the LC circuit.

7. The powertrain circuit of claim 6,

the motor controller calibrates carrier images of a first phase, a second phase and a third phase of the motor in a circumferential range in an off-line environment;

determining a carrier reversal strategy based on amplitudes of a first phase carrier, a second phase carrier and a third phase carrier of the carrier image, wherein the carrier reversal strategy comprises the following steps:

8. A power battery heating method of an electric automobile is characterized by comprising the following steps:

configuring a powertrain circuit, the powertrain circuit comprising: the power supply is arranged on the power assembly circuit; the motor controller is connected in parallel with two ends of the power supply and comprises a first phase, a second phase and a third phase which form a three-phase circuit; the LC circuit is connected between the power supply and the motor controller in parallel; the motor comprises a first winding, a second winding and a third winding which form three-phase windings, wherein the first winding, the second winding and the third winding are respectively connected with the first phase, the second phase and the third phase in parallel, the first phase comprises a switch tube S1 and a switch tube S2 which are connected in series and connected to a power assembly circuit in parallel; the second phase comprises a switch tube S3 and a switch tube S4 which are connected in series and are connected to the power assembly circuit in parallel; the third phase comprises a switch tube S5 and a switch tube S6 which are connected in series and are connected to the power assembly circuit in parallel; one end of the first winding is connected between the switch tube S1 and the switch tube S2; one end of the second winding is connected between the switch tube S3 and the switch tube S4; one end of the third winding is connected between the switch tube S5 and the switch tube S6;

9. The power cell heating method according to claim 8, further comprising the steps of:

10. The power cell heating method of claim 9, further comprising the steps of: