CN114537226B - Electric vehicle powertrain circuit and power battery heating method - Google Patents

Abstract

The invention provides a powertrain circuit of an electric vehicle and a power battery heating method. The powertrain circuit includes: a power supply, which is located on the powertrain circuit; and a motor controller, which is connected in parallel to both ends of the power supply and includes a three-phase circuit. The first, second and third phases of , the second winding and the third winding are connected in parallel with the first phase, the second phase and the third phase respectively; the motor controller detects the resonant frequency of the LC circuit and sets the carrier frequency of the first phase, the second phase and the third phase The modulation is equal to the resonant frequency so that the inverter delivers maximum input current to the power supply to maximize the heating effect of the power supply. After adopting the above technical solution, the problems of long consumption time and large energy loss when the electric vehicle power battery is heated at low temperature can be solved. At the same time, it can also solve the problem that other pulse heating functions cannot heat the battery during driving.

Description

Electric vehicle powertrain circuit and power battery heating method

Technical field

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

Background technique

With the rapid development of electric vehicles, the main problems that should be solved are the user's cruising range and charging speed. Among them, when the electric vehicle switches from starting to driving, if the battery is in a low temperature state, the output voltage, maximum allowable power, cruising range and life of the battery will be greatly affected. , the battery can operate normally only after the battery warms up to normal operating temperature. Therefore, having a battery heating function allows the battery to operate at a suitable temperature, allowing the battery to perform as it should under various working conditions and extending the battery life.

In traditional solutions, external equipment such as PTC is usually used to heat the battery. However, on the one hand, this solution increases the hardware cost, and on the other hand, the heating efficiency is not high. Due to the thermal resistance of the heat conduction path, a lot of heat is dissipated in the air. Other newer solutions control the inverter to charge and discharge the motor, thereby generating pulse current to heat the battery. However, this type of solution has the disadvantage that the heating efficiency is not high enough and it can only be used in the parking state.

Therefore, a new powertrain circuit and power battery heating method for electric vehicles are needed to achieve the most efficient heating of the power battery.

Contents of the invention

In order to overcome the above technical shortcomings, the purpose of the present invention is to provide a powertrain circuit and a power battery heating method for an electric vehicle, which can solve the problems of long consumption time and large energy loss when the electric vehicle power battery is heated at low temperature.

The invention discloses a powertrain circuit of an electric vehicle, which is installed in the electric vehicle. The powertrain circuit includes:

Power supply, located on the powertrain circuit;

The motor controller is connected in parallel to both ends of the power supply, including the first phase, the second phase, and the third phase forming a three-phase circuit;

LC circuit, connected between the power supply and motor controller;

The motor includes a first winding, a second winding and a third winding forming 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, wherein

The first phase includes the switching tube S1 and the switching tube S2 connected in series and connected in parallel to the powertrain circuit;

The second phase includes switching tubes S3 and S4 connected in series and connected in parallel to the powertrain circuit;

The third phase includes series-connected switching tubes S5 and S6, which are connected in parallel to the powertrain circuit;

One end of the first winding is connected between switching tube S1 and switching tube S2;

One end of the second winding is connected between switching tube S3 and switching tube S4;

One end of the third winding is connected between switching tube S5 and switching tube S6;

The motor controller detects the resonant frequency of the LC circuit and modulates the carrier frequency of the first phase, the second phase, and the third phase to be equal to the resonant frequency, so that the first winding, the second winding, and the third winding form an inverter. Deliver maximum input current to the power supply to maximize the heating effect of the power supply.

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

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

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

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

The frequency at which the motor controller records the temperature rise value of the power supply or the maximum effective value of the bus current of the LC circuit is the actual resonant frequency of the LC circuit.

Preferably, the motor controller controls the carrier reverse direction 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;

According to the current angle of the motor, the motor controller controls the vector sum direction of the first, second, and third currents 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 motor controller calculates the maximum value among the first current, the second current, and the third current, and reverses the carrier wave corresponding to the maximum value current.

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

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

Preferably, the motor controller calibrates the carrier image of the first phase, the second phase, and the third phase of the motor in the circumferential range in an offline environment;

Based on the amplitudes of the first phase carrier, the second phase carrier, and the third phase carrier of the carrier image, the carrier reverse strategy is determined, where the carrier reverse strategy includes:

Every time the motor deflects 60°, the phase of the carrier wave in the first phase, the second phase, and the third phase is adjusted, and the first phase direction, the third phase direction, the second phase direction, and the first phase direction are maintained within the circumferential range. , the carrier reverse sequence of the third phase direction and the second phase direction.

The invention also discloses a power battery heating method for electric vehicles, which is characterized in that it includes the following steps:

A powertrain circuit is configured. The powertrain circuit includes: a power supply, located on the powertrain circuit; a motor controller, connected in parallel to both ends of the power supply, including the first phase, the second phase, and the third phase forming a three-phase circuit. ; LC circuit is connected in parallel between the power supply and the motor controller. The L of the LC resonant circuit here is usually composed of the parasitic inductance L of the cable connecting the motor controller and the battery. C is mainly the bus capacitance of the motor controller; the motor includes The first winding, the second winding and the third winding of the three-phase winding are formed, 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, wherein the first phase includes The switch tubes S1 and S2 are connected in series and are connected in parallel to the powertrain circuit; the second phase includes the switch tube S3 and the switch S4 in series and are connected in parallel to the powertrain circuit; the third phase includes the series connected switch tubes S3 and S4. Switching tube S5 and switching tube S6 are connected in parallel to the powertrain circuit; one end of the first winding is connected between switching tube S1 and switching tube S2; one end of the second winding is connected between switching tube S3 and switching tube S4; One end of the third winding is connected between switching tube S5 and switching tube S6;

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

Preferably, the following steps are also included:

The motor controller controls the carrier reverse direction of any one of the first phase, the second phase, and the third phase.

Preferably, the following steps are also included:

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

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

After adopting the above technical solution, compared with the existing technology, it has the following beneficial effects:

1. Achieve efficient heating of power batteries under optimal carrier frequency modulation;

2. Solve the problem that electric vehicle power battery heating circuits require additional equipment and devices and reduce costs;

3. Through carrier interleaving, the effective current value of the motor is transmitted to the busbar and then to the power supply side to achieve high-frequency heating of the power battery;

4. The function of using the motor winding heating does not interfere with the function of the vehicle during normal operation, thus realizing the heating function when the vehicle is running.

Description of the drawings

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

Figure 2 is a three-phase current waveform diagram of the motor when the motor controller controls the motor DC in a preferred embodiment of the present invention;

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

Figure 4 is a frequency-gain curve diagram of an LC circuit in accordance with a preferred embodiment of the present invention;

Figure 5 is a vector sum schematic diagram of the first current, the second current and the third current on the first phase, the second phase and the third phase in accordance with the first embodiment of the present invention;

6 is a vector sum schematic diagram of the first current, the second current, and the third current on the first phase, the second phase, and the third phase in accordance with the second embodiment of the present invention.

Detailed ways

The advantages of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

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

The terminology used in this 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," "the" and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will also be understood that the term "and/or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, the information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of the present disclosure, the first information may also be called second information, and similarly, the second information may also be called first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "when" or "in response to determining."

In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientations or positional relationships indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not Any indication or implication that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation should not be construed as a limitation on the invention.

In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or both. The internal connection between components may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms can be understood according to the specific situation.

In the following description, suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention and have no specific meaning in themselves. Therefore, "module" and "component" can be used interchangeably.

Referring to Figure 1, a schematic circuit topology diagram of a powertrain circuit of an electric vehicle in accordance with a preferred embodiment of the present invention is shown. In this embodiment, the powertrain circuit is provided in the electric vehicle and specifically includes:

-power supply

A power source, such as a battery, battery pack, etc., is a device installed in an electric vehicle to provide electric energy output for the electric vehicle. When the power in the power supply is used up, it needs to be charged. Therefore, the power supply is set on the powertrain circuit, and other devices on the powertrain circuit input current to the power supply.

-Motor Controller

The motor controller is usually the nerve center that connects the motor and the battery. It is used to adjust the various performances of the electric vehicle. It not only ensures the basic safety and precise control of the vehicle, but also allows the battery and motor to exert sufficient power. strength. In this embodiment, the motor controller is different from its original function (or based on the original function) and adds a power charging configuration. That is to say, the motor controller in this embodiment is used both for For motor control, it is also used for charging control of the power supply. Specifically, the motor controller is connected in parallel at both ends of the power supply, and has the first phase, the second phase, and the third phase forming a three-phase circuit, which are commonly understood U, V, and W phases (the first phase, the second phase, and the second phase). The corresponding relationship between the phases, the third phase and the U, V, and W phases is not limited in the present invention, and any phase can be regarded as the first phase, and so on). Similarly, in this embodiment, in addition to being used to control the motor, the three-phase circuit will also affect the charging state of the power supply by the powertrain circuit.

-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 includes an inductor L1 and a capacitor C1. The inductor L1 is connected to one end of the power supply. The capacitor C1 is connected in parallel to both ends of the power supply and is located behind the inductor L1. It should be emphasized that L1 referred to in the present invention is mainly composed of the parasitic inductance of the wiring harness between the battery and the inverter. Generally, in the existing technology, the inductance L1 will not be increased (this will increase the circuit load. On the contrary, now In technology, cable structures are often used). Preferably, the reactance of C1 can also be regarded as the equivalent resistance ESR of the capacitor, which together with the inductor L1, the capacitor C1, and the internal resistance of the power supply form a second-order circuit.

-Motor

The motor is a device in an electric vehicle that converts electrical energy into mechanical energy. In this embodiment, the motor includes a first winding, a second winding and a third winding forming three-phase windings, and the first winding, the second winding and the third winding are parallel to the first phase, the second phase and the third phase respectively. Connect to complete the basic control of the motor by the motor controller.

With the above configuration, when the motor starts, the three-phase winding of the motor forms a three-phase inductor. The first phase, the second phase, and the third phase will be used as the switching bridge arm of the boost powertrain circuit, and the generated electric energy will pass through The switching bridge arm is fed into the power supply, thereby heating the power supply.

Furthermore, the specific component configuration of the powertrain circuit is as follows: the first phase includes a series-connected switch tube S1 and a switch tube S2, which are connected in parallel to the powertrain circuit; the second phase includes a series-connected switch tube S3 and a switch tube. The tube S4 is connected in parallel to the powertrain circuit; the third phase includes the switching tube S5 and the switching tube S6 connected in series, and is connected in parallel to the powertrain circuit; one end of the first winding is connected to the switching tube S1 and the switching tube S2; one end of the second winding is connected between switching tube S3 and switching tube S4; one end of the third winding is connected between switching tube S5 and switching tube S6.

In order to maximize the efficiency of improving the heating (warming) effect of the motor on the power supply, that is, under the same motor input current, make the bus current of the power supply as large as possible. In this embodiment, the motor controller will detect the LC circuit resonant frequency, and modulate the carrier frequency 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 resonant state, refer to Figure 2 and Figure 3, the effective value of the bus current is consistent with the effective value of the three-phase 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 will increase significantly, thereby increasing the input current value to the power supply.

It can be understood that for those skilled in the art, the generally held view is that in the powertrain circuit, the LC circuit has minimal impact on the circuit, even if the resonant frequency is not consistent with the carrier frequency, so The reduced input current should be minimal. However, after experimental verification, it was found that when the resonant frequency is consistent with the carrier frequency, the output voltage increases by about 20%, which is a change that cannot be ignored, resulting in a corresponding increase in the bus current by 20%. This result can break the traditional solidification concept. The resonance control of the LC circuit can also improve the heating effect of the power supply, and this heating effect should be the optimal solution among all existing heating solutions.

In a preferred embodiment, referring to Figure 4, in order to accurately determine the resonant frequency of the LC circuit, the motor controller will draw or measure (offline) the frequency-gain curve of the LC circuit at each frequency, and based on the fitted Curve, extract the frequency corresponding to the maximum gain in the frequency-gain curve. It can be understood that when drawing the frequency-gain curve, the motor controller can detect the size of the bus current in real time to determine the gain effect of the motor's output current on the bus current at each frequency. Once the resonant frequency of the LC circuit is obtained, the motor controller will control the switching frequency of the first phase, the second phase, and the third phase, so that the carrier frequency of the motor matches the resonant frequency modulation, so that the power supply current of the power supply and the LC circuit's The effective values of bus current and capacitor current are consistent.

Furthermore, in order to determine the resonant frequency of the LC circuit more accurately, the motor controller will calculate the theoretical resonant frequency based on the capacitance data of the capacitor C1 of the LC circuit and the inductance data of the inductor L1. For example, the calculation formula that can be used is: Preferably, the internal resistance of the battery and the equivalent resistance of the cable can be considered to calculate a more accurate resonant frequency. On both sides of the theoretical resonant frequency, you can repeatedly calculate the gain values at other frequencies (you can also directly detect the temperature rise value of the power supply or the effective value of the bus current of the LC circuit) to determine whether the theoretical resonant frequency is the real resonant frequency. If At a non-theoretical resonant frequency, the temperature rise value of the power supply is greater than the temperature rise value of the power supply at the theoretical resonant frequency. The frequency at which the temperature rise value of the power supply or the effective value of the bus current of the LC circuit is the maximum will be recorded at each frequency, which is the frequency of the LC circuit. actual resonant frequency.

In a further preferred embodiment, in order to further improve the heating efficiency of the power supply, the motor controller will also control the carrier reverse direction of any one of the first phase, the second phase, and the third phase. Usually after the electric vehicle is started, there are first current, second current and third current on the first phase, second phase and third phase. In order to achieve less impact on the operating state of the motor, for example, usually 0 torque control, the vector sum of the first current, the second current and the third current is controlled to be 0. However, in this embodiment, the carrier wave of a certain phase current is selected to be reversed so that the vector sum is not zero. After the carrier wave of a certain phase current is reversed, it can effectively reduce the time when the three upper tubes or three lower tubes of the motor are turned on at the same time, and transfer the effective value of the motor's output current to the bus side as much as possible, and then transfer it to the battery support. way to achieve high-frequency heating of power batteries.

It should be emphasized again that the carrier reversal strategy is often considered in the art to have no impact or improvement on battery heating. Even the mainstream concept is that once carrier reversal is performed, it will have a negative impact on the thermal stress on the bus capacitance. However, under this working condition, the battery heating effect can be effectively improved, overcoming the prejudice in the industry.

Furthermore, 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 this technical field, when an electric vehicle is started, the usual practice is for the motor controller to control the switching frequency of the first phase, the second phase and the third phase so that the motor output is alternating current. Power charging. That is, the waveform of the motor output current is a sine wave. However, when using the reverse carrier heating method, the output current form of the motor can be ignored, such as square wave direct current and triangular wave alternating current. Improved heating efficiency can be achieved at any switching frequency. At the same time, in order to still achieve zero torque control of the motor, in this embodiment, the motor controller will obtain the current angle of the motor, and control the first current, second phase, and third phase on the first phase, the second phase, and the third phase through dq transformation. The vector sum direction of the second current and the third current coincides with the d-axis direction of the current angle. The above dq transformation, see Figure 5, refers to converting the vector sum of the first current, the second current, and the third current into a vector sum of currents on the d-axis and q-axis at the current angle. And in order to achieve 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 (the q-axis current is 0 at this time). Under the above control requirements, the motor controller will calculate the maximum value of the first current, the second current, and the third current, and the phase selected in the carrier direction will select the first current, the second current, and the third current. The phase corresponding to the maximum value is reversed. As a result, the current value in the reverse direction of the carrier wave is the largest, which will maximize the heating effect on the power battery.

In the above embodiment, for the specific implementation of carrier reversal, the SVPWM/SPWM control strategy can be used to reverse one phase of the carrier. The full name of SPWM is (Sinusoidal PWM), sinusoidal pulse width modulation. Its basic principle is the area equivalence principle, that is, when narrow pulses with equal impulses but different shapes are applied to a link with inertia, the effect is basically the same. In other words, through a series of narrow pulse signals with different shapes, the integrals corresponding to the corresponding time are equal (the areas are equal), and the final effect is the same. Therefore, SPWM is to input a pulse sequence of equal amplitude to equivalent a sine wave, so the pulse time width of the output high basically changes in a sinusoidal pattern. SVPWM (space voltage vector PWM) is a pulse width modulation wave generated by a specific switching mode composed of six power switching elements of a three-phase power inverter, which can make the output current waveform as close as possible to the ideal sine waveform. Space voltage vector PWM is different from traditional sinusoidal PWM. It starts from the overall effect of the three-phase output voltage and focuses on how to make the motor obtain an ideal circular flux trajectory. Compared with SPWM, SVPWM technology has smaller harmonic components of the winding current waveform, which reduces the motor torque ripple and makes the rotating magnetic field more circular. It also greatly improves the utilization of the DC bus voltage and makes it easier to realize digitization.

It can be understood that in the above embodiments, the electric vehicle is started but not yet driven. But it is understandable that users' usage habits of electric vehicles are that after getting in the car and starting the vehicle, they step on the accelerator to keep the electric vehicle in a driving state. Therefore, preferably or alternatively, in the above state, the motor controller will calculate the equivalent first current, second current and third current of the first phase, the second phase and the third phase based on the SVPWM/SPWM algorithm. The q-axis current and the d-axis current, for example, first give the reference currents in the d-axis and q-axis directions, and based on the Iq regulator (the adjustment module for the q-axis current) and the Id regulator (the adjustment module for the d-axis current), According to the d-axis, q-axis and three-phase transformation rules (or the d-axis, q-axis and fixed α-axis, β-axis change rules), after the carriers are interleaved (that is, when the forward carrier is the largest, the reverse carrier is the smallest), the mutual Quadrature or SVPWM control, thereby controlling the motor, can calculate the equivalent q-axis current and d-axis current of the first, second, and third phases of the first, second, and third phases (see Figure 6) . The q-axis current is used to enhance the motor torque, usually called active current, and the d-axis current is used to weaken the magnetic flux, usually called reactive current. The reactive current will be transported to the bus side to heat the power battery. Specifically, when the electric vehicle is in a driving state, the motor controller controls the q-axis current and d-axis current of the motor based on the SVPWM/SPWM algorithm so that the motor operates in a normal operating state. After the carrier wave of one phase is reversed by fixed control, the effective value of the reactive current of the motor will be transferred to the power battery, that is, the equivalent d-axis after the carrier wave of one of the first current, the second current, and the third current is reversed. The current supplements the bus current of the LC circuit. Furthermore, if the d-axis current is increased under high power factor, the effective value of the current on the power battery side can also be increased.

In a further preferred embodiment, the phase selection in the carrier direction is not fixed, but is adjusted in time according to the angle of the motor. It can be understood that in the above embodiment, the carrier wave direction of the phase with the largest current value is selected to be reversed. However, during the rotation of the rotor of the motor, the phase with the largest current value is always changing. Therefore, the carrier wave direction is reversed. Phase will also be controlled by changes. The specific implementation is to calibrate the carrier image of the first phase, the second phase and the third phase of the motor in the circumferential range (every 360°) in an offline environment (such as an experimental environment). It can be known from the carrier image , the current signal amplitudes of the first phase, the second phase, and the third phase are alternately the largest. For example, when the absolute value of the first current of the first phase is the largest, the switching conditions of the second phase and the third phase should be as opposite as possible. , therefore, the carrier wave of the first phase needs to be reversed at this time. At the same time, it can be seen from the carrier image that in each cycle, there will be 6 phase transformations of the maximum current value, in the order of the first phase, the third phase, and the second phase. Therefore, based on the carrier image, the first phase carrier, The amplitudes of the second phase carrier and the third phase carrier determine the carrier reversal strategy. The carrier reversal strategy includes: adjusting the phase of the carrier reversal in the first, second and third phases for every 60° deflection of the motor, and The carrier reverse sequence of the first reverse direction, the third reverse direction, the second reverse direction, the first reverse direction, the third reverse direction, and the second reverse direction is maintained within the circumferential range. That is to say, only one phase is carrier reversed at a time, and when the carrier of the next phase is reversed, the phase of the previous carrier reversed will be maintained. It should be noted that the basis of the three-phase carrier wave image with carrier reverse flipping is the three-phase current signal, and the modulated wave signal cannot be used. Because the change in power factor will cause the current phase and voltage phase (modulation wave phase) to shift. Using three-phase current signals can ensure that this strategy is effective under different power factors. And every time the carrier wave reverses, the THD of the motor's output current will increase, so it is necessary to reduce the number of carrier wave reverses as much as possible. According to the above, there are six carrier reversals in each fundamental wave cycle, and the cycle is reversed to ensure that only one phase carrier is flipped each time. Then, six carrier reversals will be performed in the fundamental wave cycle.

The invention also discloses a power battery heating method for an electric vehicle, which includes the following steps: configuring a power assembly circuit. The power assembly circuit includes: a power supply, located on the power assembly circuit; and a motor controller connected in parallel to both power sources. The terminal includes the first phase, the second phase and the third phase forming a three-phase circuit; the LC circuit is connected between the power supply and the motor controller; the motor includes the first winding, the second winding and the third winding forming the three-phase winding. Three windings, and the first winding, the second winding and the third winding are connected in parallel with the first phase, the second phase and the third phase respectively, where the first phase includes the switching tube S1 and the switching tube S2 connected in series, and are connected in parallel to On the powertrain circuit; the second phase includes switch tubes S3 and S4 connected in series and connected in parallel to the powertrain circuit; the third phase includes switch tubes S5 and S6 connected in series and connected in parallel to the powertrain circuit. On the circuit; one end of the first winding is connected between switching tube S1 and switching tube S2; one end of the second winding is connected between switching tube S3 and switching tube S4; one end of the third winding is connected between switching tube S5 and switching tube S6 time; the motor controller detects the resonant frequency of the LC circuit, and modulates the carrier frequency of the first phase, the second phase, and the third phase to be equal to the resonant frequency, so that the first winding, the second winding, and the third winding form the inverse The inverter delivers maximum input current to the power supply to maximize the heating effect of the power supply.

Preferably or optionally, the method further includes the following steps: the motor controller controls the carrier reverse direction of any one of the first phase, the second phase, and the third phase.

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

It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person familiar with the art may change or modify the above-disclosed technical contents into equivalent and effective embodiments. , as long as they do not deviate from the content of the technical solution of the present invention, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims (6)

1. The utility model provides a power assembly circuit of electric automobile, locates in the electric automobile, its characterized in that, power assembly circuit includes:

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 the first phase, the second phase and the third phase in parallel, and the motor comprises a motor body, a motor body and a motor

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

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

the third phase comprises a switching tube S5 and a switching tube S6 which are connected in series and 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 switching tube S3 and the switching tube S4;

one end of the third winding is connected between the switching tube S5 and the switching 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 the inverter formed by the first winding, the second winding and the third winding transmits the maximum input current to the power supply to maximize the heating effect of the power supply, wherein

The motor controller controls the carrier wave of any one of the first phase, the second phase and the third phase to reverse;

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

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

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 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.

3. The powertrain circuit of claim 2, wherein,

the motor controller calculates theoretical resonant frequency according to capacitance data and 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 on two sides of the theoretical resonant frequency repeatedly until the temperature rise value of the power supply or the bus current effective value of the LC circuit is maximum;

and the frequency with the maximum temperature rise value of the power supply or the bus current effective value of the LC circuit is recorded as the actual resonant frequency of the LC circuit by the motor controller.

4. The powertrain circuit of claim 1,

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

the motor controller controls the vector sum direction 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 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 corresponding to the maximum value current is reversed.

5. The powertrain circuit of claim 1,

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 reverse strategy based on the amplitudes of the first phase carrier, the second phase carrier and the third phase carrier of the carrier image, wherein the carrier reverse strategy comprises:

the motor adjusts the phase of carrier inversion in the first phase, the second phase and the third phase every 60 degrees of deflection, and maintains the carrier inversion sequence of the first phase inversion, the third phase inversion, the second phase inversion, the first phase inversion, the third phase inversion and the second phase inversion in the circumferential range.

6. The power battery heating method of the electric automobile 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 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 the first phase, the second phase and the third phase in parallel, the first phase comprises a switching tube S1 and a switching tube S2 which are connected in series, and the switching tube S1 and the switching tube S2 are connected to a power assembly circuit in parallel; the second phase comprises a switching tube S3 and a switching tube S4 which are connected in series and connected to the power assembly circuit in parallel; the third phase comprises a switching tube S5 and a switching tube S6 which are connected in series and 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 switching tube S3 and the switching tube S4; one end of the third winding is connected between the switching tube S5 and the switching 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 to maximize the heating effect of the power supply;

the motor controller controls the carrier wave of any one of the first phase, the second phase and the third phase to reverse;

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

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