Vehicle, energy conversion device and control method thereof

Abstract

The technical solution of the present application provides a vehicle, an energy conversion device and a control method thereof. The energy conversion device includes a bridge arm converter, a motor winding and an energy storage element. The motor winding, the energy storage element and the battery are connected to form a battery heating circuit. The control method includes: when a battery heating instruction is obtained, the bridge arm converter is controlled at an initial charge and discharge frequency to charge and discharge the battery and the energy storage element so that the battery is self-heated; during the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery. The present application adjusts the bridge arm converter according to the change of the battery parameters, and at the same time adjusts the charge and discharge frequency of the battery to achieve control of the heating power of the battery, thereby avoiding the problems of low heating efficiency and high noise of the battery during the battery heating process.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a vehicle, an energy conversion device and a control method thereof. Background Art

[0002] With the widespread use of new energy, batteries can be used as power sources in various fields. The performance of batteries will be affected by the different environments in which they are used as power sources. For example, the performance of batteries in low temperature environments will be greatly reduced compared to normal temperatures. For example, at zero temperature, the discharge capacity of the battery will decrease as the temperature decreases. Under -30°C conditions, the discharge capacity of the battery is basically 0, making the battery unusable. In order to use the battery in a low temperature environment, the battery needs to be preheated before use.

[0003] like Figure 1 As shown, the prior art includes a bridge arm converter 101, a motor 102, and a battery 103. When the battery 103 is in the discharging process, the transistor VT1 and the transistor VT6 in the bridge arm converter 101 are triggered to be turned on at the same time, and the current flows out from the positive electrode of the battery 103, passes through the transistor VT1 and the transistor VT6, and the two stator inductors of the motor 102, and returns to the negative electrode of the battery 103. The current rises, and the energy is stored in the two stator inductors; when the battery 103 is in the charging process, as shown in FIG. Figure 2 As shown, transistor VT1 and transistor VT6 are disconnected at the same time, and the current flows from the two stator inductors of the motor 102 and the bridge arm converter 101 through the two discharge diodes VD4 and VD3 back to the battery 102, and the current decreases. Repeating the above two processes, the battery is in a rapid alternating state of charging and discharging. Due to the existence of the internal resistance of the battery, a large amount of internal heat is generated, and the temperature rises rapidly. However, the prior art has the following problems: in the process of heating the battery, since the battery charge and discharge frequency is fixed, with the increase of the battery heating time and the change of the external environment, the ideal battery heating current cannot be output at the original battery charge and discharge frequency, thereby affecting the battery heating efficiency. At the same time, the noise generated by the motor is also very large, which seriously affects the driver's driving experience. Summary of the invention

[0004] The purpose of the present application is to provide a vehicle, an energy conversion device and a control method thereof, which can adjust the heating efficiency of the battery by adjusting the bridge arm converter according to the battery parameters, thereby avoiding the problems of low heating efficiency and high noise during the battery heating process.

[0005] The present application is implemented as follows. In a first aspect, the present application provides a control method for an energy conversion device, wherein the energy conversion device comprises:

[0006] A bridge arm converter, a motor winding and an energy storage element, wherein the bridge arm converter, the motor winding, the energy storage element and a battery are connected to form a battery heating circuit;

[0007] The control method comprises:

[0008] When a battery heating instruction is obtained, the bridge arm converter is controlled at an initial charge and discharge frequency to charge and discharge the battery and the energy storage element so that the battery is self-heated;

[0009] During the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery.

[0010] A second aspect of the present application provides an energy conversion device, the energy conversion device comprising:

[0011] A bridge arm converter, a motor winding and an energy storage element, wherein the bridge arm converter, the motor winding, the energy storage element and a battery are connected to form a battery heating circuit;

[0012] The energy conversion device further comprises a control module, wherein the control module is used for:

[0013] When a battery heating instruction is obtained, the bridge arm converter is controlled at an initial charge and discharge frequency to charge and discharge the battery and the energy storage element so that the battery is self-heated;

[0014] During the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery.

[0015] A third aspect of the present application provides a vehicle, comprising the energy conversion device described in the second aspect.

[0016] The technical solution of the present application provides a vehicle, an energy conversion device and a control method thereof. The energy conversion device includes a bridge arm converter, a motor winding and an energy storage element. The motor winding, the energy storage element and the battery are connected to form a battery heating circuit. The control method includes: when a battery heating instruction is obtained, the bridge arm converter is controlled at an initial charge and discharge frequency to charge and discharge the battery and the energy storage element so that the battery is self-heated; during the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery. The present application adjusts the bridge arm converter according to the change of the battery parameters, and at the same time adjusts the charge and discharge frequency of the battery to achieve control of the heating power of the battery, thereby avoiding the problems of low heating efficiency and high noise of the battery during the battery heating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 It is a current flow diagram of a motor control circuit provided by the prior art;

[0019] Figure 2 is another current flow diagram of a motor control circuit provided by the prior art;

[0020] Figure 3 is a circuit diagram of an energy conversion device provided in Example 1 of the present application;

[0021] Figure 4 is another circuit diagram of an energy conversion device provided in Example 1 of the present application;

[0022] Figure 5 is another circuit diagram of an energy conversion device provided in Example 1 of the present application;

[0023] Figure 6 is a flow chart of a control method for an energy conversion device provided in Example 1 of the present application;

[0024] Figure 7 This is a specific flow chart of step S10 of a control method for an energy conversion device provided in Example 1 of the present application;

[0025] Figure 8 is a specific flow chart of step S20 in a control method for an energy conversion device provided in Example 1 of the present application;

[0026] Fig. 9 is a current flow diagram of an energy conversion device provided in Example 1 of the present application;

[0027] Fig.10 is another current flow diagram of an energy conversion device provided in Example 1 of the present application;

[0028] Fig.11 is another current flow diagram of an energy conversion device provided in Example 1 of the present application;

[0029] Fig.12 This is another current flow diagram of an energy conversion device provided in Example 1 of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0031] In order to illustrate the technical solution of the present application, a specific embodiment is provided below for illustration.

[0032] Embodiment 1 of the present application provides an energy conversion device, the energy conversion device comprising:

[0033] The bridge arm converter, the motor winding and the energy storage element are connected with the battery to form a battery heating circuit.

[0034] As a first implementation method of the connection relationship between the bridge arm converter, the motor winding and the energy storage element, Figure 3 As shown, the energy conversion device includes:

[0035] A bridge arm converter 101, wherein the first ends of the bridge arms of the bridge arm converter 101 are connected together to form a first bus terminal, and the second ends of the bridge arms of the bridge arm converter 101 are connected together to form a second bus terminal;

[0036] An energy storage element C1, wherein a first end of the energy storage element C1 is connected to a first bus terminal, and a second end of the energy storage element C1 is connected to a second bus terminal;

[0037] The motor winding 102, the first end of the motor winding 102 is respectively connected to the midpoint of each phase bridge arm of the bridge arm converter 101, the second end of the motor winding 102 is commonly connected to the positive electrode of the battery 103, and the negative electrode of the battery 103 is connected to the first bus terminal;

[0038] Among them, the bridge arm converter 101 includes M bridge arms, the first end of each bridge arm in the M bridge arms is connected together to form a first bus terminal of the bridge arm converter 101, the second end of each bridge arm in the M bridge arms is connected together to form a second bus terminal of the bridge arm converter 101, each bridge arm includes two power switch units connected in series, the power switch unit can be a transistor, IGBT, MOS tube or other device types, the midpoint of each bridge arm is formed between the two power switch units, the motor includes M-phase windings, the first end of each phase winding in the M-phase windings is connected one-to-one with the midpoint of each bridge arm in a group of M bridge arms, the second end of each phase winding in the M-phase windings is connected together to form a neutral point, and the neutral point is connected to the positive pole of the battery 103.

[0039] When M=3, the bridge arm converter 101 is a three-phase inverter, which includes three bridge arms, the first end of each bridge arm in the three bridge arms is connected in common to form a first bus terminal of the bridge arm converter 101, and the second end of each bridge arm in a group of three bridge arms is connected in common to form a second bus terminal of the bridge arm converter 101; the three-phase inverter includes a first power switch unit, a second power switch unit, a third power switch unit, a fourth power switch unit, a fifth power switch and a sixth power switch, the first power switch unit and the fourth power switch unit form a first bridge arm, the second power switch unit and the fifth switch unit form a second bridge arm, the third power switch unit and the sixth switch unit form a third bridge arm, one end of the first power switch unit, the third power switch unit and the fifth power switch unit are connected in common to form a first bus terminal of the three-phase inverter, and one end of the second power switch unit, the fourth power switch unit and the sixth power switch unit are connected in common to form a second bus terminal of the three-phase inverter.

[0040] Among them, the motor winding 102 includes a three-phase winding, the first end of each phase winding in the three-phase winding is connected one-to-one with the midpoint of each bridge arm in the three bridge arms, the second end of each phase winding in the three-phase winding is connected together to form a neutral point, the first end of the first phase winding of the motor winding 102 is connected to the midpoint of the first bridge arm, the first end of the second phase winding of the motor winding 102 is connected to the midpoint of the second bridge arm, and the first end of the third phase winding of the motor winding 102 is connected to the midpoint of the third bridge arm.

[0041] Among them, the first power switch unit in the three-phase inverter includes a first upper bridge arm VT1 and a first upper bridge diode VD1, the second power switch unit includes a second lower bridge arm VT2 and a second lower bridge diode VD2, the third power switch unit includes a third upper bridge arm VT3 and a third upper bridge diode VD3, the fourth power switch unit includes a fourth lower bridge arm VT4 and a fourth lower bridge diode VD4, the fifth power switch unit includes a fifth upper bridge arm VT5 and a fifth upper bridge diode VD5, the sixth power switch unit includes a sixth lower bridge arm VT6 and a sixth lower bridge diode VD6, the motor is a three-phase four-wire system, and can be a permanent magnet synchronous motor or an asynchronous motor, and the three-phase windings are connected at one point and connected to the positive pole of the battery 103.

[0042] In another embodiment, if Figure 4 As shown, the energy conversion device further includes a first switch module 104 and a second switch module 105. The first end of the first switch module 104 is connected to the first end of the energy storage element C1, and the second end of the first switch module 104 is connected to the positive electrode of the battery 103; the second switch module 105 is connected between the neutral point of the motor winding 102 and the positive electrode or negative electrode of the battery 103.

[0043] Among them, the first switch module 104 is used to realize the conduction or disconnection between the battery 103 and the energy storage element C1 according to the control signal, so that the battery 103 charges or stops charging the energy storage element C1; the second switch module 105 is used to realize the conduction or disconnection between the motor winding 102 and the battery 103 according to the control signal, so that the battery 103 outputs electrical energy to the motor winding 102 or stops outputting electrical energy.

[0044] In this embodiment, the bridge arm converter 101 and the motor winding 102 in the battery heating circuit can reuse the three-phase inverter and the motor in the vehicle motor drive circuit, and the energy storage module reuses the bus capacitor of the motor drive circuit, using the same module for different functions. By setting the first switch module 104 and the second switch module 105, components are reused to achieve multiple function switching, thereby increasing the utilization of the bridge arm converter 101 and the motor winding 102 and saving costs.

[0045] When the first switch module 104 is turned on and the second switch module 105 is turned off, the battery 103, the first switch module 104, the bridge arm converter 101, the energy storage element C1, and the motor winding 102 form a motor drive circuit. At this time, the motor output power is achieved by controlling the bridge arm converter 101.

[0046] Among them, when the first switch module 104 is turned off and the second switch module 105 is turned on, the battery 103, the second switch module 105, the motor winding 102, the bridge arm converter 101, and the energy storage element C1 form a battery heating circuit. At this time, the battery 101 and the energy storage element C1 are heated by controlling the bridge arm converter 101 to charge and discharge.

[0047] When the first switch module 104 is turned off and the second switch module 105 is turned on, Figure 4 Can be equivalent to Figure 3 The first bus terminal of the bridge arm converter 101 is connected to the first end of the energy storage element C1, the second bus terminal of the bridge arm converter 101 is connected to the second end of the energy storage element C1, the first end of the motor winding 102 is connected to the bridge arm converter 101, the second end of the motor winding 102 is connected to the first end of the battery 101, and the second end of the battery 103 is connected to the second bus terminal of the bridge arm converter 101, forming a battery heating circuit.

[0048] The battery heating circuit includes a discharge circuit and a charging circuit. The discharge circuit refers to the discharge of the energy storage element C1 by the battery 103 through the motor winding 102 and the bridge arm converter 101. At this time, current flows out of the battery 103, and the current flows into the energy storage element C1 through the motor winding 102 and the bridge arm converter 101 to charge the energy storage element C1; the charging circuit refers to the charging of the battery 103 by the energy storage element C1 through the motor and the bridge arm converter 101. At this time, current flows out of the energy storage element C1, and the current flows through the bridge arm converter 101 and the motor winding 102 and flows into the battery 103. Due to the internal resistance in the battery 103, when the discharge circuit and the charging circuit are working, the internal resistance of the battery 103 will generate heat, thereby increasing the temperature of the battery 103.

[0049] When the battery heating circuit is working, the battery 103, the motor winding 102, and the bridge arm converter 101 form a discharge energy storage circuit, and the battery 103, the motor winding 102, the bridge arm converter 101, and the energy storage element C1 form a discharge energy release circuit; the energy storage element C1, the bridge arm converter 101, the motor winding 102, and the battery 103 form a charging energy storage circuit, and the motor winding 102, the battery 103, and the bridge arm converter 101 form a charging energy release circuit.

[0050] Among them, the discharge circuit includes a discharge energy storage circuit and a discharge energy release circuit, and the charging circuit includes a charging energy storage circuit and a charging energy release circuit. When the discharge energy storage circuit is controlled to work by the bridge arm converter 101, the battery 103 outputs electric energy to store energy in the winding of the motor; when the discharge energy release circuit is controlled to work by the bridge arm converter 101, the battery 103 discharges and the winding of the motor releases energy to charge the energy storage element C1; when the charging energy storage circuit is controlled to work by the bridge arm converter 101, the energy storage element C1 discharges to charge the battery 103, and the winding of the motor winding 102 stores energy; when the charging energy release circuit is controlled to work by the bridge arm converter 101, the winding of the motor winding 102 releases energy to charge the battery 103. By controlling the bridge arm converter 101, the discharge process of the battery 103 to the energy storage element C1 and the charging process of the energy storage element C1 to the battery 103 are alternately performed, so that the temperature of the battery 103 is increased; in addition, by controlling the duty cycle of the PWM control signal of the bridge arm converter 101, the effective value of the current flowing through the battery heating circuit is adjusted. Controlling the duty cycle is equivalent to controlling the conduction time of the upper bridge arm and the lower bridge arm. By controlling the conduction time of the upper bridge arm or the lower bridge arm to be longer or shorter, the current in the battery heating circuit will increase or decrease, and the heating power generated by the battery 103 can be adjusted.

[0051] It should be noted that, in the process of controlling the operation of the discharge circuit and the charging circuit, the discharge energy storage circuit, the discharge energy release circuit, the charging energy storage circuit and the charging energy release circuit in the discharge circuit can be controlled to operate in sequence, and the effective value of the current flowing through the battery heating circuit can be adjusted by controlling the duty cycle of the PWM control signal of the bridge arm converter 101. Alternatively, the discharge energy storage circuit and the discharge energy release circuit in the discharge circuit can be controlled to be alternately turned on for discharge, and then the charging energy storage circuit and the charging energy release circuit in the charging circuit can be controlled to be alternately turned on for discharge, and the effective values ​​of the current flowing through the discharge circuit and the charging circuit can be adjusted respectively by controlling the duty cycle of the PWM control signal of the bridge arm converter 101.

[0052] This embodiment controls the bridge arm converter 101 to operate the battery heating circuit, so that the battery 103 in the discharge circuit discharges the energy storage element C1 and the energy storage element C1 in the charging circuit charges the battery 103, thereby increasing the temperature of the battery 103. The bridge arm converter 101 can also be controlled to adjust the current in the self-heating circuit of the battery 103 and adjust the heating power generated by the battery 103.

[0053] As a second embodiment of the connection relationship between the bridge arm converter 101, the motor winding 102 and the energy storage element, Figure 5As shown, the first bus terminal of the bridge arm converter 101 is connected to the positive electrode of the battery 103, and the second bus terminal of the bridge arm converter 101 is connected to the negative electrode of the battery 103; the first end of the motor winding 102 is connected to the bridge arm converter 101, the second end of the motor winding 102 is connected to the first end of the energy storage element C2, and the second end of the energy storage element C2 is connected to the second bus terminal of the bridge arm converter 101, forming a battery heating circuit.

[0054] Among them, the difference between this embodiment and the above embodiment lies in the different connection methods between the modules. The specific structures of the modules are the same, and can be referred to the above embodiment, which will not be repeated here.

[0055] Among them, for the battery heating circuit, the battery heating circuit includes a discharge circuit and a charging circuit. The discharge circuit refers to the discharge of the energy storage element C2 by the battery 103 through the bridge arm converter 101 and the motor winding 102. At this time, current flows out of the battery 103, and the current flows into the energy storage element C2 through the bridge arm converter 101 and the motor winding 102 to charge the energy storage element C2; the charging circuit refers to the charging of the battery 103 by the energy storage element C2 through the motor winding 102 and the bridge arm converter 101. At this time, current flows out of the energy storage element C2, and the current flows through the motor winding 102 and the bridge arm converter 101 and flows into the battery 103. Due to the internal resistance in the battery 103, when the discharge circuit and the charging circuit are working, the battery 103 has current flowing in and out, which will cause the internal resistance of the battery to generate heat, thereby increasing the temperature of the battery 103.

[0056] like Figure 6 As shown, the control method of the energy conversion device includes step S10 and step S20, and the specific steps are as follows:

[0057] Step S10: When a battery heating instruction is obtained, the bridge arm converter is controlled at an initial charge and discharge frequency to charge and discharge the battery and the energy storage element, so that the battery is self-heated.

[0058] Among them, obtaining a battery heating instruction refers to an instruction that causes the battery and other modules to form a heating circuit and generate heat. When the battery heating instruction is obtained, the battery heating circuit formed by connecting the bridge arm converter, the motor winding, the energy storage element and the battery is in a working state, and the bridge arm converter is controlled by the initial charge and discharge frequency to put the battery heating circuit in a working state, wherein the initial charge and discharge frequency can be determined by multiple charge and discharge frequencies preset for the battery.

[0059] Among them, the step of controlling the bridge arm converter with the initial charge and discharge frequency to charge and discharge the battery and the energy storage element in step S10 also includes obtaining the initial charge and discharge frequency, such as Figure 7As shown, the step of obtaining the initial charge and discharge frequency includes step S101, step S102 and step S103, and the specific steps are as follows:

[0060] Step S101: Acquire multiple charging and discharging frequencies of the battery.

[0061] In step S101, the charge and discharge frequency of the battery can be multiple values, for example, 50HZ, 95HZ, 250HZ, etc. There is a corresponding relationship between the charge and discharge frequency of the battery and the effective value of the current of the battery heating circuit. For example, the charge and discharge frequency of 50HZ corresponds to an effective current of 50A, the charge and discharge frequency of 95HZ corresponds to an effective current of 60A, the charge and discharge frequency of 250HZ corresponds to an effective current of 80A, and so on.

[0062] Step S102: Under each charge and discharge frequency of the battery, the duty cycle of the PWM control signal is adjusted to control the bridge arm converter to obtain the effective current value corresponding to each charge and discharge frequency.

[0063] Among them, different battery charge and discharge frequencies correspond to different effective values ​​of the current in the battery heating circuit. Different duty cycles of the PWM control signal at the same battery charge and discharge frequency also correspond to different effective values ​​of the current in the battery heating circuit. Therefore, by keeping the battery charge and discharge frequency unchanged, the effective value of the current flowing through the battery heating circuit can be adjusted by adjusting the duty cycle of the PWM control signal.

[0064] Step S103: Obtain the effective current value corresponding to each charge and discharge frequency, obtain the maximum effective current value according to the effective current value, and use the charge and discharge frequency corresponding to the maximum effective current value as the initial charge and discharge frequency.

[0065] Among them, the duty cycle of the PWM control signal is adjusted at each charge and discharge frequency in turn, and the effective current value corresponding to each duty cycle at the charge and discharge frequency is recorded by a current sensor, so as to obtain multiple effective current values ​​corresponding to each charge and discharge frequency, obtain the maximum effective current value, and obtain the corresponding frequency control bridge arm converter according to the maximum effective current value.

[0066] Step S20. During the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery.

[0067] The battery parameters include the battery temperature, the effective current value of the battery or the battery heating time.

[0068] In step S20, adjusting the charge and discharge frequency of the battery heating circuit according to the battery parameters includes:

[0069] When at least one of the battery temperature, the effective current value of the battery or the heating time of the battery reaches a preset condition, the target charge and discharge frequency corresponding to the maximum effective current under the current battery parameters is re-determined.

[0070] The preset condition corresponding to the battery temperature is: the battery temperature rises by C1;

[0071] The preset condition corresponding to the effective current value of the battery is: the effective current value of the battery decreases by A1;

[0072] The preset condition corresponding to the battery heating time is: the battery heating time increases by T1.

[0073] For example, the temperature of the battery is collected through a temperature sensor, and when it is detected that the temperature rises by 5 degrees Celsius, it is considered to have met the preset condition; the effective current value of the battery is obtained through a current sensor, and when the effective current value of the battery drops by 5A, it is considered to have met the preset condition; the heating time of the battery is detected through a timer, and when the heating time of the battery reaches 3 minutes, it is considered to have met the preset condition, wherein the collection interval of the battery temperature and current is at least greater than one battery charge and discharge cycle. When it is detected that the above parameters meet the preset conditions, the charge and discharge frequency of the battery is adjusted.

[0074] As an implementation method, Figure 8 As shown, the target charge and discharge frequency corresponding to the maximum effective current under the current battery parameters is re-determined, including:

[0075] Step S201: Re-acquire multiple charging and discharging frequencies of the battery.

[0076] In step S201, a plurality of charge and discharge frequencies of the battery are re-acquired, for example, the charge and discharge frequencies are 50 Hz, 95 Hz, 250 Hz, 500 Hz, 666 Hz, 760 Hz, 850 Hz, 1000 Hz, and 1300 Hz.

[0077] Step S202: Under each charge and discharge frequency of the battery, the duty cycle of the PWM control signal is adjusted to control the bridge arm converter to obtain the effective current value corresponding to each charge and discharge frequency.

[0078] The charge and discharge frequency of the battery is kept unchanged, and the effective value of the current flowing through the battery heating circuit can be adjusted by adjusting the duty cycle of the PWM control signal.

[0079] Step S203: Obtain the effective current value corresponding to each charge and discharge frequency under the current battery parameters, obtain the maximum effective current value according to the effective current value, and use the charge and discharge frequency corresponding to the maximum effective current value as the initial charge and discharge frequency.

[0080] Among them, the duty cycle of the PWM control signal is adjusted at each charge and discharge frequency in turn, and the effective current value corresponding to each duty cycle at the charge and discharge frequency is recorded by a current sensor, so as to obtain multiple effective current values ​​corresponding to each charge and discharge frequency, obtain the maximum effective current value, and obtain the corresponding frequency control bridge arm converter according to the maximum effective current value.

[0081] The technical effect of this embodiment is that when the inductance and capacitance values ​​of the system circuit change, the battery charge and discharge frequency can be adjusted in real time within the range of tens of hertz to one thousand hertz, and the duty cycle can be adjusted within each battery charge and discharge frequency to obtain the effective value of the current, and the effective value of the current is compared to obtain the maximum effective value of the current, and the bridge arm converter is controlled according to the duty cycle corresponding to the maximum effective value of the current, so that the system performs battery self-heating at a charge and discharge frequency close to the resonant frequency point of the circuit, thereby ensuring that the output battery heating current value is optimal, and finally achieving a better battery self-heating effect, and because the charge and discharge frequency of the battery used is close to the resonant frequency of the circuit, the noise problem caused by the motor during use is reduced. In addition, this method can also improve the heating speed, high efficiency, and avoid the problem of adverse effects on electronic devices and battery packs in the circuit and reduced service life caused by excessive motor torque pulsation and current spikes.

[0082] Embodiment 1 of the present application provides a control method for an energy conversion device, the energy conversion device includes a bridge arm converter, a motor winding and an energy storage element, the motor winding, the energy storage element and the battery are connected to form a battery heating circuit, and the control method includes: when a battery heating instruction is obtained, the bridge arm converter is controlled at an initial charge and discharge frequency, so that the battery and the energy storage element are charged and discharged, so that the battery is self-heated; during the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery. The present application adjusts the bridge arm converter according to the change of the battery parameters, and at the same time adjusts the charge and discharge frequency of the battery, so as to control the heating power of the battery, thereby avoiding the problems of low heating efficiency and high noise of the battery during the battery heating process.

[0083] The present embodiment is described in detail below through a specific circuit structure:

[0084] like Figure 3As shown, the energy conversion device includes a bridge arm converter 101, a motor winding 102, a bus capacitor C1, a first end of the capacitor C1 connected to a first bus terminal of the bridge arm converter 101, midpoints of the three bridge arms of the bridge arm converter 101 are respectively connected to three coils of the motor winding 102, a connection point of the three coils of the motor winding 102 is connected to a first end of a battery 103, and a second end of the battery 103 is connected to a second bus terminal of the bridge arm converter 101 and a second end of the bus capacitor C1.

[0085] Among them, the bridge arm converter 101 includes a first power switch unit, a second power switch unit, a third power switch unit, a fourth power switch unit, a fifth power switch unit and a sixth power switch unit. The first power switch unit and the fourth power switch unit form a first bridge arm, the third power switch unit and the sixth power switch unit form a second bridge arm, the fifth power switch unit and the second power switch unit form a third bridge arm, one end of the first power switch unit, the third power switch unit and the fifth power switch unit are connected together and constitute a first bus terminal of the bridge arm converter, one end of the second power switch unit, the fourth power switch unit and the sixth power switch unit are connected together and constitute a second bus terminal of the bridge arm converter, the first phase coil of the motor 102 is connected to the midpoint of the first bridge arm, the second phase coil of the motor 102 is connected to the midpoint of the second bridge arm, and the third phase coil of the motor 102 is connected to the midpoint of the third bridge arm.

[0086] The first power switch unit in the bridge arm converter 101 includes a first upper bridge arm VT1 and a first upper bridge diode VD1, the second power switch unit includes a second lower bridge arm VT2 and a second lower bridge diode VD2, the third power switch unit includes a third upper bridge arm VT3 and a third upper bridge diode VD3, the fourth power switch unit includes a fourth lower bridge arm VT4 and a fourth lower bridge diode VD4, the fifth power switch unit includes a fifth upper bridge arm VT5 and a fifth upper bridge diode VD5, the sixth power switch unit includes a sixth lower bridge arm VT6 and a sixth lower bridge diode VD6, the three-phase AC motor is a three-phase four-wire system, and can be a permanent magnet synchronous motor or an asynchronous motor, and a neutral line is drawn out at the midpoint of the three-phase coil connection.

[0087] The first stage is the discharge energy storage circuit operation: Fig. 9 As shown, when the lower bridge arm of the bridge arm converter 101 is turned on, the current flows out from the positive electrode of the battery 103, passes through the motor 102 and the lower bridge arm of the bridge arm converter 101 (the second lower bridge arm VT2, the fourth lower bridge arm VT4, and the sixth lower bridge arm VT6), and flows back to the negative electrode of the battery 103, and the current continues to increase.

[0088] The second stage is the discharge freewheeling circuit operation: Fig.10As shown, when the lower arm of the bridge arm converter 101 is turned off and the upper arm is turned on, the current starts from the positive electrode of the battery 103, passes through the motor 102 and the upper arm of the bridge arm converter 101 (the first upper bridge diode VD1, the third upper bridge diode VD3, and the fifth upper bridge diode VD5), and then charges the positive electrode of the bus capacitor C1. The current continuously decreases to zero, and the inductance energy storage is reduced to zero. The battery 103 and the winding inductance of the motor 102 are discharged together to charge the bus capacitor C1, and the voltage of the bus capacitor C1 increases to a certain maximum value.

[0089] The third stage is the operation of the charging energy storage circuit: Fig.11 As shown, the lower bridge arm of the control arm converter 101 is disconnected and the upper bridge arm is closed. When the upper bridge arm of the bridge arm converter 101 is turned on, the current starts from the positive electrode of the bus capacitor C1, passes through the upper bridge arms (the first upper bridge arm VT1, the third upper bridge arm VT3, and the fifth upper bridge arm VT5) of the bridge arm converter 101, and then charges the positive electrode of the battery 103 through the motor 102. The current first increases and then decreases continuously, and the voltage of the bus capacitor C1 decreases continuously.

[0090] The fourth stage is the charging freewheeling circuit operation: Fig.12 As shown, when the lower bridge arm of the bridge arm converter 101 is turned on, the current flows out from the negative electrode of the battery 103, passes through the lower bridge arm of the bridge arm converter 101 (the second lower bridge diode VD2, the fourth lower bridge diode VD4, the sixth lower bridge diode VD6) and the motor 102, and flows back to the positive electrode of the battery, and the current continues to decrease, and the voltage of the bus capacitor C1 will continue to decrease.

[0091] In the first and second stages, the battery 103 discharges externally, and at the end of the first stage, the discharge current reaches a maximum. In the third and fourth stages, the battery 103 is charged, and at a certain moment in the third stage, the charging current reaches a maximum. In the second stage, the bus capacitor C1 is charged, and the voltage of the bus capacitor C1 rises to the highest. In the third stage, the bus capacitor C1 is discharged, and the voltage of the bus capacitor C1 drops to the lowest.

[0092] The upper and lower bridge arms of the bridge arm converter 101 are complementary pulse controlled. Under the premise that the control cycle remains unchanged, the longer the opening time of the lower bridge arm is, the greater the maximum value of the charge and discharge current of the battery 103 is. At the same time, the higher the maximum voltage of the bus capacitor C1 is, the greater the maximum value of the charge and discharge current of the battery 103 will be, and the greater the heating power of the internal resistance of the battery 103 will be. On the contrary, the shorter the opening time of the lower bridge arm is, the smaller the maximum value of the charge and discharge current of the battery 103 is, and the smaller the maximum voltage of the bus capacitor C1 is, the smaller the maximum value of the charge and discharge current of the battery 103 is, and the heating power of the internal resistance of the battery 103 will be.

[0093] From the above, it can be seen that under the premise of a certain control cycle, the charge and discharge current of the battery is mainly adjusted by controlling the duty cycle, and the internal heat generation power of the battery is positively correlated with the conduction time of the lower bridge arm. The control cycle will be mainly determined by the AC internal resistance of the battery. The control cycle is selected with the maximum heating power as the goal, but the control cycle will affect the variation range of the capacitor voltage, and the variation range of the capacitor voltage is negatively correlated with the cycle. Increasing the duty cycle of the lower bridge arm can increase the charge and discharge current of the battery, that is, increase the internal heating power of the battery. On the contrary, reducing the duty cycle of the lower bridge arm can reduce the charge and discharge current of the battery, that is, reduce the internal heating power of the battery. During the entire heating process, the status of related components such as electronic control and motors is monitored in real time. If there are abnormal conditions in current, voltage, and temperature, stop heating immediately to ensure heating safety.

[0094] The above four processes are continuously cycled, so that the battery is continuously and rapidly charged and discharged. Due to the existence of the internal resistance of the battery, a large amount of heat is generated, causing the battery to heat up rapidly.

[0095] The control strategy proposed in this application that can adjust the charge and discharge frequency in real time is to control the IGBT through software to achieve the battery self-heating function. The specific implementation steps are as follows:

[0096] The following is an introduction to the debugging and control phase of the system. The main task of the debugging and control phase is to control the IGBT according to the control strategy of this patent to realize the charging and discharging function of the battery. The specific debugging steps are as follows:

[0097] Step 1: Follow Figure 3 Connect the system hardware circuit as shown to ensure that all components function well.

[0098] Step 2: Configure the carrier frequency of the system and calculate the corresponding period value T in the program.

[0099] Step 3: The charging and discharging frequency values ​​of the system are given as F1=50HZ, F2=95HZ, F3=250HZ, F4=500HZ, F5=666HZ, F6=760HZ, F7=830HZ, F8=1000HZ, and F9=1250HZ respectively.

[0100] Step 4: Based on the input and output voltage levels and the control principle of the hardware circuit of the current system, the initial duty cycle M of the control signal is given, the counter of the control cycle configuration controller is calculated according to step 2, and the comparison value of the counter is determined (the comparison value is used to change the duty cycle of the control signal).

[0101] Step 5: According to the given 9 charge and discharge frequency values, the control signal is applied to the three-phase bridge arm of the electronic control within each charge and discharge frequency (the control of the three-phase bridge arm remains consistent), and the effective value of the charge and discharge current is changed by adjusting the duty cycle to achieve the battery charge and discharge function. The maximum value of the battery heating current at the corresponding frequency is calculated respectively, and recorded as T1, T2, T3, T4, T5, T6, T7, T8, and T9 respectively.

[0102] Step 6: Compare the above 9 effective values ​​of battery heating current, and select the charge and discharge frequency corresponding to the maximum current for battery self-heating. This frequency point is the resonant frequency point under the current capacitance and inductance value state of the system circuit, that is, at this frequency, the effective current value of the battery is the maximum.

[0103] Step 7: During the charging and discharging process, always monitor the battery temperature rise, battery heating current value, battery heating time, motor three-phase current value, C1 capacitor side current value, battery voltage value, C1 capacitor voltage value, motor winding and IGBT temperature and other state parameters. When one of the following three conditions is met, return to step 5 and recalculate the 9 battery heating current values ​​T1-T9. The three conditions include: ① battery temperature rise> 5 degrees Celsius; ② battery heating current value drops by 5A; ③ battery heating time> 3min.

[0104] Among them, when the battery temperature sensor detects that the battery temperature rise is greater than 5 degrees Celsius, the charge and discharge frequency is adjusted once; after the temperature rises by 5 degrees Celsius again, it is adjusted again.

[0105] When the effective current value collected by the battery current sensor drops by 5A, the charge and discharge frequency is adjusted once; when the effective current value drops by another 5A, it is adjusted again;

[0106] Or if the battery heating time exceeds 3 minutes, the charge and discharge frequency is adjusted once; if the heating time exceeds the next 3 minutes, it is adjusted again;

[0107] Among them, the collection interval time of battery temperature collection and current collection is at least greater than one charge and discharge cycle.

[0108] Step 8: If all three conditions in step 7 are not met, the battery self-heating is continued at the current charge and discharge frequency until the heating is completed.

[0109] Step 9: After the battery self-heating is completed, the duty cycle of the control signal of the three-phase bridge arm of the bridge arm converter is gradually reduced to gradually reduce the effective value of the battery charge and discharge current until it is 0, and the battery charge and discharge process is completed.

[0110] Among them, the upper and lower bridge arms of the three-phase bridge arm of the bridge arm converter are complementary pulse controlled. Under the premise of unchanged control cycle, the longer the opening time of the lower bridge arm, the greater the maximum value of the battery charge and discharge current, and the higher the maximum voltage of the capacitor, the greater the maximum value of the battery charge and discharge current, and the greater the heating power of the battery internal resistance. On the contrary, the shorter the opening time of the lower bridge arm, the smaller the maximum value of the battery charge and discharge current, and the smaller the maximum voltage of the capacitor, the smaller the maximum value of the battery charge and discharge current, and the smaller the heating power of the battery internal resistance.

[0111] This application solves the problem that the original battery charging and discharging frequency cannot output the original ideal battery heating current effective value when the external conditions change. First of all, the system will only output a more ideal battery heating current effective value when it is near its resonant frequency. For example, under the current combination of inductance and capacitance values, the resonant frequency of the system is around 760HZ. The resonant frequency of the system is only determined by the inherent parameters of the circuit itself, inductance and capacitance. When the inductance and capacitance values ​​inside the system hardware change, the resonant frequency of the system also changes. During the battery self-heating process, as the heating time increases, the capacitance value in the system structure and the inductance value of the motor will change. Similarly, as the vehicle's service life increases, the inductance value of the motor will also change. When the vehicle is charged by OBC, after being connected to the charging cabinet, the inductance value of the system will also change. For the above three situations, when the capacitance and inductance change, the corresponding system resonant frequency will also change. Therefore, it is impossible to output a more ideal battery heating current under the original battery charging and discharging frequency. This new control method can adaptively adjust the battery charge and discharge frequency, so that when external conditions (such as ambient temperature, vehicle age, whether OBC charging is performed) change, it can automatically find the charge and discharge frequency around the resonant frequency point corresponding to different capacitance and inductance values, and control the system to output a better battery heating current effective value around the resonant frequency point to achieve a good battery self-heating effect.

[0112] Embodiment 2 of the present invention further provides an energy conversion device, the energy conversion device comprising:

[0113] The bridge arm converter, the motor winding and the energy storage element are connected with the battery to form a battery heating circuit;

[0114] The energy conversion device further includes a control module, which is used to:

[0115] Get vehicle status;

[0116] When the vehicle is in the heating mode, the bridge arm converter is controlled to adjust the current flowing through the battery heating circuit, so that the battery and the energy storage element are charged and discharged, so that the battery is self-heated;

[0117] The battery parameters are obtained, and the bridge arm converter is adjusted according to the battery parameters to adjust the heating power of the battery.

[0118] Among them, the specific control method of the controller can refer to the above control method, which will not be repeated here.

[0119] The bridge arm converter includes N-phase bridge arms, the motor winding includes N-phase windings, and the N-phase bridge arms are connected to the N-phase windings in a one-to-one correspondence.

[0120] In one embodiment, the bridge arm converter, the motor winding, the energy storage element and the battery are connected to form a battery heating circuit, which specifically includes: the first ends of the N-phase bridge arms are connected together to form a first bus terminal, the first bus terminal is connected to the first end of the energy storage element, the second ends of the N-phase bridge arms are connected together to form a second bus terminal, the second bus terminal is connected to the second end of the energy storage element, the first ends of the N-phase windings are respectively connected one by one to the midpoints of the N-phase bridge arms, the second ends of the N-phase windings are connected to the positive pole of the battery, and the negative pole of the battery is connected to the second bus terminal.

[0121] In another embodiment, the bridge arm converter, the motor winding, the energy storage element and the battery are connected to form a battery heating circuit, which specifically includes:

[0122] The first ends of the N-phase bridge arms are connected together to form a first bus terminal, which is connected to the positive electrode of the battery. The second ends of the N-phase bridge arms are connected together to form a second bus terminal, which is connected to the negative electrode of the battery. The first ends of the N-phase windings are respectively connected to the midpoints of the N-phase bridge arms one by one, the second ends of the N-phase windings are connected to the first end of the energy storage element, and the second end of the energy storage element is connected to the second bus terminal.

[0123] The third embodiment of the present invention further provides a vehicle, comprising the energy conversion device provided in the first embodiment above.

[0124] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A control method for an energy conversion device, characterized in that: The energy conversion device comprises: A bridge arm converter, a motor winding and an energy storage element, wherein the bridge arm converter, the motor winding, the energy storage element and a battery are connected to form a battery heating circuit; The control method comprises: When a battery heating instruction is obtained, a plurality of charging and discharging frequencies of the battery are obtained; At each charge and discharge frequency of the battery, the bridge arm converter is controlled by adjusting the duty cycle of the PWM control signal to obtain the effective current value corresponding to each charge and discharge frequency; Obtaining the current effective value corresponding to each charge and discharge frequency, obtaining a maximum current effective value according to the current effective value, and using the charge and discharge frequency corresponding to the maximum current effective value as the initial charge and discharge frequency; Controlling the bridge arm converter at an initial charge and discharge frequency to charge and discharge the battery and the energy storage element, so that the battery is self-heated; During the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery.

2. The control method according to claim 1, characterized in that: The obtaining of the battery parameters comprises: The temperature of the battery, the effective current value of the battery, or the heating time of the battery is obtained.

3. The control method according to claim 2, characterized in that: The step of adjusting the charge and discharge frequency of the battery heating circuit according to the battery parameters includes: When at least one of the temperature of the battery, the effective current value of the battery, or the heating time of the battery reaches a corresponding preset condition, re-determining a target charge and discharge frequency corresponding to the maximum effective current under current battery parameters; The charge and discharge frequency of the battery heating circuit is adjusted to a target charge and discharge frequency.

4. The control method according to claim 3, characterized in that: The preset condition corresponding to the temperature of the battery is: the temperature of the battery rises by C1; The preset condition corresponding to the effective current value of the battery is: the effective current value of the battery decreases by A1; The preset condition corresponding to the heating time of the battery is: the heating time of the battery increases by T1.

5. The control method according to claim 4, characterized in that: The re-determining the target charge and discharge frequency corresponding to the maximum effective current under the current battery parameters includes: Re-acquiring multiple charge and discharge frequencies of the battery; At each charge and discharge frequency of the battery, the duty cycle of the PWM control signal is adjusted to control the bridge arm converter to obtain the effective current value corresponding to each charge and discharge frequency under the current battery parameters; Obtain the effective current value corresponding to each charge and discharge frequency under the current battery parameters, and obtain the maximum effective current value according to the effective current value; The charge and discharge frequency corresponding to the maximum current effective value is used as the target charge and discharge frequency.

6. The control method according to claim 1, characterized in that: The bridge arm converter, the motor winding, the energy storage element and the battery are connected to form a battery heating circuit, which specifically includes: the first ends of the N-phase bridge arms are connected together to form a first bus terminal, the first bus terminal is connected to the first end of the energy storage element, the second ends of the N-phase bridge arms are connected together to form a second bus terminal, the second bus terminal is connected to the second end of the energy storage element, the first ends of the N-phase windings are connected one by one to the midpoints of the N-phase bridge arms, the second ends of the N-phase windings are connected to the positive pole of the battery, and the negative pole of the battery is connected to the second bus terminal.

7. The control method according to claim 1, characterized in that: The bridge arm converter, the motor winding, the energy storage element and the battery are connected to form a battery heating circuit, which specifically includes: The first ends of the N-phase bridge arms are connected together to form a first bus terminal, which is connected to the positive electrode of the battery. The second ends of the N-phase bridge arms are connected together to form a second bus terminal, which is connected to the negative electrode of the battery. The first ends of the N-phase windings are respectively connected to the midpoints of the N-phase bridge arms one by one, the second ends of the N-phase windings are connected to the first end of the energy storage element, and the second end of the energy storage element is connected to the second bus terminal.

8. An energy conversion device, characterized in that: The energy conversion device comprises: A bridge arm converter, a motor winding and an energy storage element, wherein the bridge arm converter, the motor winding, the energy storage element and a battery are connected to form a battery heating circuit; The energy conversion device further comprises a control module, wherein the control module is used for: When a battery heating instruction is obtained, a plurality of charging and discharging frequencies of the battery are obtained; At each charge and discharge frequency of the battery, the bridge arm converter is controlled by adjusting the duty cycle of the PWM control signal to obtain the effective current value corresponding to each charge and discharge frequency; Obtaining the current effective value corresponding to each charge and discharge frequency, obtaining a maximum current effective value according to the current effective value, and using the charge and discharge frequency corresponding to the maximum current effective value as the initial charge and discharge frequency; Controlling the bridge arm converter at an initial charge and discharge frequency to charge and discharge the battery and the energy storage element, so that the battery is self-heated; During the battery heating process, the battery parameters are obtained, the charge and discharge frequency of the battery heating circuit is adjusted according to the battery parameters, and the bridge arm converter is controlled according to the charge and discharge frequency to adjust the current flowing through the battery heating circuit to adjust the heating power of the battery.

9. A vehicle, characterized in that: The vehicle comprises the energy conversion device according to claim 8.

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