CN217455736U - Battery heating device and car - Google Patents
Battery heating device and car Download PDFInfo
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- CN217455736U CN217455736U CN202221280160.2U CN202221280160U CN217455736U CN 217455736 U CN217455736 U CN 217455736U CN 202221280160 U CN202221280160 U CN 202221280160U CN 217455736 U CN217455736 U CN 217455736U
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Abstract
The embodiment of the application provides a battery heating device and car, and this heating device includes: the system comprises a battery pack, a three-phase inverter and a motor; the battery pack is formed by connecting a plurality of battery packs in series; the first bus end of the three-phase inverter is connected with the positive electrode of the battery pack; the second junction end of the three-phase inverter is connected with the negative pole of the battery pack; the output end of the three-phase inverter is connected with the input end of the motor; the three-phase inverter is used for changing the input current of the motor; a neutral point of the motor and a series point between any two battery packs in the battery packs form a branch; the branch circuit comprises a capacitance module. The heating device is suitable for working at high switching frequency, thereby reducing operation noise and enhancing heating effect. The capacitor module can isolate direct current or low-frequency common-mode voltage, so that the battery heating device does not need to control the electric quantity balance of the batteries connected in series, and the control software and hardware of the battery pack are simplified; the three-phase short circuit state of the motor can be quickly switched in when the high-speed driving fails, the neutral line relay does not need to be disconnected, and the safety is improved.
Description
Technical Field
The application relates to the technical field of circuits, in particular to a battery heating device and an automobile.
Background
The performance of a power battery of a new energy vehicle is poor at low temperature, and therefore, the battery of the vehicle needs to be heated when the vehicle is driven or parked for charging. In the prior art, there is a method of connecting a neutral point of a motor to a midpoint of a battery pack connected in series and heating a battery by using a midpoint current. However, in this method, when the heating current is small at a high switching frequency, the heating power is small. Due to the existence of non-ideal factors, even if the duty ratios of the upper and lower bridge arms of the three-phase inverter bridge of the three-phase inverter are completely symmetrical, the average value of the neutral current cannot be absolutely zero. In the past, the capacity of the upper battery pack and the capacity of the lower battery pack are unbalanced. Therefore, the mean value of the neutral current must be controlled by software and hardware, so as to maintain the capacity balance of the upper and lower battery units. Except that the three-phase inverter controls the mean line current, a battery management system of the automobile needs to estimate the electric quantity of an upper battery pack and a lower battery pack at the same time and gives a midpoint mean current reference value instruction according to the electric quantity. This undoubtedly greatly increases the hardware and software complexity of the battery management system.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application aims at providing a battery heating device and an automobile.
In a first aspect, an embodiment of the present application provides a battery heating apparatus, including:
the system comprises a battery pack, a three-phase inverter and a motor;
the battery pack is formed by connecting a plurality of battery packs in series;
the first bus end of the three-phase inverter is connected with the positive electrode of the battery pack;
the second junction end of the three-phase inverter is connected with the negative electrode of the battery pack;
the output end of the three-phase inverter is connected with the input end of the motor;
the three-phase inverter is used for changing the input current of the motor;
a neutral point of the motor and a series point between any two of the battery packs form a branch circuit;
the branch circuit comprises a capacitance module.
In the implementation process, the heating current of the system in high-frequency working can be improved through the resonance between the capacitor module and the common-mode inductor of the motor, so that the whole device is more suitable for working in the environment with high switching frequency. High switching frequencies may avoid the frequency bands of the human ear that are sensitive to noise, thereby reducing acoustic noise. The high-frequency current can generate a remarkable skin effect, and the internal resistance of the battery is increased, so that the internal resistance heating of the battery is enhanced. The capacitor module can isolate low-frequency common-mode voltage, so that the battery heating device can modulate a three-phase inverter by adopting various three-phase PWM modulation without limitation in a driving state. Because of the isolation effect of the capacitor module, the average value of the branch current is definitely zero, so that branch average current control software and hardware are not required to be set, the circuit is simplified, the battery management system of the matched automobile does not need to detect the electric quantity of the upper battery pack and the lower battery pack at the same time, a midpoint average current reference value instruction is given according to the electric quantity, and the hardware complexity and the software complexity of the battery management system are reduced.
Further, the capacitor module and a common mode inductor of the motor form a resonant circuit;
the resonant frequency of the resonant circuit is higher than the switching frequency of the three-phase inverter.
Further, the three-phase inverter includes: a first bridge arm, a second bridge arm and a third bridge arm;
the first bridge arm is connected with a U-phase line of the motor;
the second bridge arm is connected with a V-phase line of the motor;
and the third bridge arm is connected with the W phase line of the motor.
Further, the first bridge leg, the second bridge leg, and the third bridge leg each include:
a first power switch and a second power switch;
the drain electrode of the first power switch is connected with the first bus end;
the source electrode of the first power switch is connected with the drain electrode of the second power switch;
the source electrode of the second power switch is connected with the second bus end;
the source electrode of the first power switch of the first bridge arm is connected with the U-phase line;
the source electrode of the first power switch of the second bridge arm is connected with the V-phase line;
and the source electrode of the first power switch of the third bridge arm is connected with the W phase line.
Further, the branch circuit further comprises a relay, and the relay is connected with the capacitor module in series.
Further, the first bridge arm, the second bridge arm, and the third bridge arm further include: a first diode and a second diode;
an anode of the first diode and a drain of the first power switch;
a cathode of the first diode and a source of the first power switch;
an anode of the second diode and a drain of the second power switch;
a cathode of the second diode and a source of the second power switch.
Further, the battery pack is formed by connecting a plurality of batteries in parallel.
Further, when the device works, the three-phase inverter is driven by one modulation wave of SPWM, SVPWM and DPWM.
Further, the battery pack is formed by connecting two battery packs in series.
In a second aspect, an embodiment of the present application provides an automobile, including the battery heating apparatus according to the first aspect.
Additional features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the above-described techniques.
In order to make the aforementioned objects, features and advantages of the present application comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of a battery heating apparatus provided in an embodiment of the present application;
fig. 2 is another schematic structural diagram of a battery heating apparatus according to an embodiment of the present disclosure;
fig. 3 is a diagram illustrating the relationship between the switching frequency and the branch resonant current.
Marking: 1-a battery pack; 2-a three-phase inverter; 21-a first leg; 22-a second leg; 23-a third leg; 211-a first power switch; 212-a second power switch; 3, a motor; 4-a capacitive module; 5-relay.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
Example 1
Referring to fig. 1, an embodiment of the present application provides a battery heating apparatus, including:
the system comprises a battery pack 1, a three-phase inverter 2 and a motor 3;
the battery pack 1 is formed by connecting a plurality of battery packs in series;
the first bus end of the three-phase inverter 2 is connected with the anode of the battery pack 1;
the second bus end of the three-phase inverter 2 is connected with the negative pole of the battery pack 1;
the output end of the three-phase inverter 2 is connected with the input end of the motor 3;
the three-phase inverter 2 is used for changing the input current of the motor 3;
the motor 3 is connected in a star shape;
a neutral point of the motor 3 and a series point between any two of the battery packs form a branch circuit;
the branch comprises a capacitive module 4.
It is understood that the three-phase inverter 2 is connected to a control circuit (not shown in the figure).
In the implementation process, the resonance between the capacitor module 4 and the common-mode inductor of the motor 3 can improve the heating current of the system during high-frequency work, so that the whole device is more suitable for working in an environment with high switching frequency. High switching frequencies may avoid the frequency bands of the human ear that are sensitive to noise, thereby reducing acoustic noise. The high-frequency current can generate a remarkable skin effect, and the internal resistance of the battery is increased, so that the internal resistance heating of the battery is enhanced. The capacitor module 4 can isolate low-frequency common-mode voltage, so that the battery heating device can modulate the three-phase inverter 2 by adopting various three-phase PWM modulation without limitation in a driving state. Because of the isolation effect of the capacitor module 4, the average value of the branch current is definitely zero, so that branch average current control software and hardware are not required to be set, the circuit is simplified, the battery management system of the matched automobile does not need to detect the electric quantity of the upper battery pack and the lower battery pack at the same time, a midpoint average current reference value instruction is given according to the electric quantity, and the hardware complexity and the software complexity of the battery management system are reduced.
Further, the capacitor module 4 and the common mode inductor of the motor 3 form a resonant circuit;
the resonant frequency of the resonant circuit is higher than the switching frequency of the three-phase inverter 2.
Further, the three-phase inverter includes: first leg 21, second leg 22, and third leg 23;
the first bridge arm 21 is connected with a U-phase line of the motor 3;
the second bridge arm 22 is connected with a V-phase line of the motor 3;
and the third bridge arm 23 is connected with the W phase line of the motor 3.
In the implementation process, the current is adjusted by first arm 21, second arm 22, and third arm 23, so that the magnitude of the current flowing in motor 3 can be changed, and the output torque of motor 3 can be changed.
It will be appreciated that first leg 21, second leg 22, and third leg 23 are also connected to a control circuit that forms a motor controller for regulating the current through the motor.
Further, the first leg 21, the second leg 22, and the third leg 23 further include: a first diode and a second diode;
an anode of the first diode and a drain of the first power switch 211;
a cathode of the first diode and a source of the first power switch 211;
an anode of the second diode and a drain of the second power switch 212;
a cathode of the second diode and a source of the second power switch 212.
In the implementation process, the first diode and the second diode are adopted to protect the circuit, so that the power switch can be prevented from being broken down by high voltage.
Further, the battery pack is formed by connecting a plurality of batteries in parallel.
It is understood that the battery pack 1 includes a plurality of battery packs connected in series, and each battery pack includes a plurality of batteries connected in parallel.
As a preferred embodiment, the number of battery packs between the connection point of the branch and the battery pack 1 to the first end of the battery pack 1 and the number of battery packs between the connection point of the battery pack 1 to the second end of the battery pack 1 are equal. Based on this, uniform heating can be ensured.
It should be noted that, in the embodiment of the present application, it is not limited that one end of the branch is necessarily connected to the midpoint of the battery pack 1. That is, the number of battery packs between the connection point of the branch and the battery pack 1 to the first end of the battery pack 1 and the number of battery packs between the connection point of the battery pack 1 to the second end of the battery pack 1 may not be equal.
When the device works, the three-phase inverter is driven by one of the modulating waves of SPWM, SVPWM and DPWM, which can bring better motor driving performance. For example, in the SVPWM modulation mode, the three-phase inverter 2 may output a higher ac voltage to the motor, so that the motor 3 outputs a higher power; SVPWM also means less motor current ripple, thereby improving motor 3 switching acoustic noise. DPWM means that the three-phase inverter 2 can reduce switching loss, thereby reducing self-heating or outputting a larger current to the motor 3 to increase motor torque and power.
Further, the branch circuit further comprises a relay 5, and the relay 5 is connected with the capacitor module in series.
In the implementation process, the opening and closing of the battery heating function can be realized through the opening and closing of the relay 5.
In the prior art, vehicles are generally suitable for permanent magnet synchronous motors. In an automobile equipped with a permanent magnet synchronous motor, at a high speed, if the three-phase inverter 2 or the motor itself or other related components have a fault, the three-phase inverter 2 needs to be controlled to enable the motor 3 to enter a three-phase short circuit state. Therefore, if heating is performed in a driving state, the motor 3 is required to enter a three-phase short-circuit state upon occurrence of a failure, and the relay 5 must first be turned off, and the motor 3 must enter the three-phase short-circuit state after confirming that the relay 5 is turned off. Otherwise, the voltage of the series point of the battery directly acts on two ends of the common mode inductor, and the motor 3 instantly generates huge common mode current to burn out the motor 3. In this embodiment, the battery voltage is blocked by the capacitor module 4 due to the function of the capacitor module 4, so the motor 3 can directly enter a three-phase short circuit without waiting for the relay 5 to be turned off, which significantly increases the safety of the vehicle.
In a possible embodiment, the capacitive module 4 comprises: a first capacitor. The first capacitor is connected to the relay 5.
Based on the above embodiments, the working principle of the circuit is explained in the embodiments of the present application to further illustrate the beneficial effects of the battery heating apparatus.
Based on the resonance of the common-mode inductance and capacitance module 4 of the motor 3, the natural resonance frequency of the device can be obtained by the following formula:
wherein L is N C is common mode inductance of the motor 3 (which may include common mode inductance generated by windings of the motor 3, stray inductance of wires, or additional inductance added to the neutral point of the motor 3, not shown in the diagram), C N The capacitance value of the capacitive module 4.
The expression for the heating current in the device is:
wherein, U B The voltage of the whole battery pack 1 is obtained; f. of s Is the switching frequency of the power switches in the three-phase inverter 2; illustratively, the capacitance value L of the inductor is taken N 15uH, CN of capacitance value of capacitance module 4 is 7.5uF, and natural resonant frequency f of the device is at this time N Is 15 kHz.
The relationship between switching frequency and branch resonant current is shown in fig. 3. Generally, the three-phase inverter 2 drives the motor to operate, and when the battery is not heated, the switching frequency is about 10kHz, and may be changed to some extent according to different working conditions (generally, the switching frequency is reduced to reduce loss). When heating is required, the switching frequency is increased to near the 15kHz resonant frequency. For example, when the switching frequency is adjusted to 13kHz, the effective value of the branch current is increased to 400A, and the battery can be rapidly heated by the large current. By adjusting the switching frequency, the effective value of the branch current can be controlled, thereby adjusting the battery heating frequency. If no heating is required at all, the bypass relay is opened.
Further, the capacitance of the capacitor module 4 makes the resonance point of the resonant circuit at several kilohertz, even over 10kHz, far exceeding the current electrical frequency of the motor 3 (for example, 15000rpm of a four-pole motor, fac equal to 1 kHz). The resonant network is a capacitor at low frequency, and presents large impedance, and at the moment, the low-frequency common-mode voltage can only generate small low-frequency common-mode current, so that the operation of the motor 3 cannot be influenced, and the circuit can normally work in a driving state.
Neglecting the internal resistance of the battery, under SVPWM modulation, the fundamental wave amplitude of the low-frequency common-mode current generated by the low-frequency common-mode voltage is obtained as follows:
exemplarily, L N ＝15uH，C N ＝7.5uF，f N At 15kHz at a maximum speed of 15000rpm (f) ac 1kHz, 1 voltage utilization rate m), 5.4A of low-frequency common-mode current amplitude, and completely negligible. At other speeds, the low frequency common mode current will only be lower. Therefore, after the capacitor module 4 is added, no matter the SPWM, SVPWM or various DPWMs are adopted in the vehicle running state, the low-frequency common-mode voltage can be isolated, so that the three-phase PWM modulation mode can be freely selected in the vehicle running state, and the advantages of various three-phase PWM modulation modes can be exerted.
Example 2
An embodiment of the present application provides an automobile including the battery heating apparatus of embodiment 1.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. A battery heating apparatus, comprising:
the system comprises a battery pack, a three-phase inverter and a motor;
the battery pack is formed by connecting a plurality of battery packs in series;
the first bus end of the three-phase inverter is connected with the positive electrode of the battery pack;
a second junction end of the three-phase inverter is connected with the negative electrode of the battery pack;
the output end of the three-phase inverter is connected with the input end of the motor;
the three-phase inverter is used for changing the input current of the motor;
a neutral point of the motor and a series point between any two of the battery packs form a branch circuit;
the branch circuit comprises a capacitance module.
2. The battery heating apparatus according to claim 1,
the capacitor module and a common-mode inductor of the motor form a resonant circuit;
the resonant frequency of the resonant circuit is higher than the switching frequency of the three-phase inverter.
3. The battery heating apparatus according to claim 1, wherein the three-phase inverter includes: a first bridge arm, a second bridge arm and a third bridge arm;
the first bridge arm is connected with a U-phase line of the motor;
the second bridge arm is connected with a V-phase line of the motor;
and the third bridge arm is connected with the W phase line of the motor.
4. The battery heating apparatus of claim 3, wherein the first leg, the second leg, and the third leg each comprise:
a first power switch and a second power switch;
the drain electrode of the first power switch is connected with the first bus end;
the source electrode of the first power switch is connected with the drain electrode of the second power switch;
the source electrode of the second power switch is connected with the second bus end;
the source electrode of the first power switch of the first bridge arm is connected with the U-phase line;
the source electrode of the first power switch of the second bridge arm is connected with the V-phase line;
and the source electrode of the first power switch of the third bridge arm is connected with the W phase line.
5. The battery heating apparatus of claim 1, wherein the branch further comprises a relay, the relay and the capacitance module being connected in series.
6. The battery heating apparatus of claim 4, wherein the first leg, the second leg, and the third leg further comprise: a first diode and a second diode;
an anode of the first diode and a drain of the first power switch;
a cathode of the first diode and a source of the first power switch;
an anode of the second diode and a drain of the second power switch;
a cathode of the second diode and a source of the second power switch.
7. The battery heating apparatus according to claim 1, wherein the battery pack is formed by connecting a plurality of batteries in parallel.
8. Battery heating device according to any of claims 1-7, characterized in that the device, in operation, the three-phase inverter is driven by a modulated wave of one of SPWM, SVPWM, DPWM.
9. The battery heating apparatus according to any one of claims 1 to 7, comprising:
the battery pack is formed by connecting two battery packs in series.
10. An automobile comprising the battery heating apparatus according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221280160.2U CN217455736U (en) | 2022-05-25 | 2022-05-25 | Battery heating device and car |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221280160.2U CN217455736U (en) | 2022-05-25 | 2022-05-25 | Battery heating device and car |
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| Publication Number | Publication Date |
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| CN217455736U true CN217455736U (en) | 2022-09-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202221280160.2U Active CN217455736U (en) | 2022-05-25 | 2022-05-25 | Battery heating device and car |
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- 2022-05-25 CN CN202221280160.2U patent/CN217455736U/en active Active
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