CN203193255U - Electric automobile motor over-current protection circuit - Google Patents
Electric automobile motor over-current protection circuit Download PDFInfo
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- CN203193255U CN203193255U CN 201320116678 CN201320116678U CN203193255U CN 203193255 U CN203193255 U CN 203193255U CN 201320116678 CN201320116678 CN 201320116678 CN 201320116678 U CN201320116678 U CN 201320116678U CN 203193255 U CN203193255 U CN 203193255U
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Abstract
The utility model discloses an electric automobile motor over-current protection circuit, comprising an over-current primary confirmation circuit and an over-current secondary confirmation circuit, wherein a current acquisition element in the primary confirmation circuit acquires a motor three-phase current signal and converts the signal into a voltage signal, the voltage signal is filtered and then inputted into a dual-comparator so as to be compared with upper limit voltage and lower limit voltage, and a comparison result is taken as a first signal and inputted into a master control chip; and in the over-current secondary confirmation circuit, the voltage signal goes through an RC low-pass filter and a clamping diode to form a second signal, and the second signal is inputted to the master control chip. On one hand, the electric automobile motor over-current protection circuit is capable of eliminating the possibility that a motor and a motor controller system stop to operate due to over-current protection triggered by signal interferences; on the other hand, the electric automobile motor over-current protection circuit is capable of timely turning off the motor and the motor controller system to effectively protect the motor and a motor controller from being damaged, when a motor three-phase line really has an over-current case.
Description
Technical Field
The utility model relates to a motor control technical field especially relates to an electric automobile motor overcurrent protection circuit.
Background
The traditional fuel automobile industry faces huge challenges due to energy shortage and climate warming, and energy-saving and environment-friendly electric automobiles are more and more concerned and begin to go to the market from laboratories.
At present, the mutual conversion task of electric energy and mechanical energy on the electric automobile is completed by a motor. When the motor is operated, if the motor controller is improperly controlled or the motor itself is abnormal, the current of the three phase lines of the motor may be increased, that is, the current is often referred to as "overcurrent". If the tolerance of the motor and motor controller components is exceeded, the components may be damaged. Therefore, the motor controller needs to adopt a corresponding strategy to avoid the motor and the motor controller from being destructively affected by over-current.
At present, all will set up special overcurrent protection scheme in the electric automobile motor controller, the way is as follows at present:
in terms of hardware, as shown in fig. 1, a three-phase current signal of the motor is converted into a voltage signal through a current acquisition element, then the voltage signal is sent to a comparison link formed by double comparators, and an output signal of the comparison link is directly sent to a main control chip as a first signal. In the comparison step, the overcurrent protection limit is set by setting the upper limit voltage and the lower limit voltage of the comparator. Once the voltage signal output by the current collecting element is higher than the upper limit voltage or lower than the lower limit voltage, the high level signal output by the comparing link is changed into a low level signal.
In terms of software, as shown in fig. 2, after receiving the low level signal, the main control chip immediately turns off the PWM signal output, and simultaneously sends an overcurrent fault code to the outside, so as to indicate to the vehicle controller that the motor and the motor controller system are in a fault state and cannot continue to operate.
However, in practical applications, the motor and the motor controller adopting the above overcurrent protection scheme often trigger overcurrent protection due to signal interference, and thus stop working. Under the condition, the safety and the driving smoothness of the vehicle are greatly influenced, and the market acceptance of the electric vehicle is also influenced to a certain extent.
SUMMERY OF THE UTILITY MODEL
The utility model discloses to motor and machine controller because of the problem that signal interference triggered overcurrent protection, provide an electric automobile motor overcurrent protection circuit. The motor and motor controller system is turned off in time when overcurrent condition really occurs on three phase lines of the motor, and the motor controller are effectively protected from being damaged.
In order to achieve the purpose, the over-current protection circuit of the electric automobile motor comprises an over-current primary confirmation circuit, wherein the over-current primary confirmation circuit comprises a current acquisition element, a filtering module, a double comparator and a main control chip, the current acquisition element acquires a three-phase current signal of the motor and converts the three-phase current signal into a voltage signal, the voltage signal is input into the double comparator after being filtered and compared with an upper limit voltage and a lower limit voltage, and a comparison result is input into the main control chip as a first signal; wherein,
the overcurrent secondary confirmation circuit comprises an RC low-pass filter and a clamping diode, a voltage signal output by the current acquisition element sequentially passes through the RC low-pass filter and the clamping diode to form a second signal, the second signal is input to the main control chip, and the main control chip controls whether a motor control signal is output or not according to the first signal and the second signal.
Preferably, the current collecting element is a hall current sensor.
Preferably, the main control chip is a digital signal processing chip.
The working method of the overcurrent protection circuit of the motor of the electric automobile comprises the following steps:
the current acquisition element acquires a three-phase current signal of the motor and converts the three-phase current signal into a voltage signal, the voltage signal is input into the double comparator after being filtered, the voltage signal is compared with the upper limit voltage and the lower limit voltage, and a comparison result is input into the main control chip as a first signal; meanwhile, the voltage signal sequentially passes through an RC low-pass filter and a clamping diode to form a second signal, and the second signal is also input to the main control chip;
when the first signal is at a low level, the overcurrent is considered to occur, and the main control chip shuts off the PWM signal output;
calculating the three-phase current value of the motor according to the second signal;
judging whether the three-phase current value of the motor exceeds a preset overcurrent protection limit value or not;
if the three-phase current value of the motor exceeds a preset overcurrent protection limit value, judging that overcurrent faults exist, sending an overcurrent fault code to the outside by a main control chip, resetting an overcurrent frequency flag bit, and finishing overcurrent fault processing; otherwise, if the three-phase current value of the motor does not exceed the preset overcurrent protection limit value, the main control chip restarts the output of the PWM signal and adds 1 to the overcurrent time flag bit;
the main control chip monitors whether the overcurrent fault occurs again within the specified time T, if the overcurrent fault occurs again within the specified time T, the overcurrent fault is judged, the main control chip shuts off PWM signal output and sends an overcurrent fault code to the outside, and the overcurrent fault processing is finished; otherwise, namely if the overcurrent fault does not occur within the specified time T, the previous overcurrent fault is judged to be signal interference triggering, the main control chip controls the motor and the motor controller system to continue to operate after clearing the overcurrent time flag bit, and the overcurrent fault processing is finished.
The preset overcurrent protection limit value is 2.5 times of the maximum value of the three-phase current signal of the motor. The prescribed time T is 20 ms.
The beneficial effects of the utility model reside in that, the overcurrent protection circuit can carry out the secondary to the overcurrent and confirm to when interference signal triggered overcurrent protection, can restart immediately after motor and machine controller system shut down, make electric automobile can continue the operation under the condition that does not stop to reset. Thus, the possibility of the motor and motor controller system ceasing to operate due to signal interference triggering over-current protection is eliminated.
In addition, when the overcurrent condition of the three-phase lines of the motor really occurs, the current value of the three-phase line of the motor calculated according to the second signal exceeds the preset overcurrent protection limit value, or the overcurrent fault can occur again within the specified time T. Under the two conditions, the motor and the motor controller system can be switched off in time, so that the motor and the motor controller are effectively protected from being damaged.
Drawings
Fig. 1 is a schematic diagram showing a circuit structure of overcurrent protection hardware in the prior art;
FIG. 2 shows a prior art over-current protection software flow diagram;
fig. 3 shows the electric vehicle motor overcurrent protection hardware circuit structure schematic diagram of the utility model.
Fig. 4 shows a flow chart of the overcurrent protection software for the motor of the electric vehicle according to the present invention.
Detailed Description
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to fig. 3 and 4.
Referring to fig. 3, the output terminal of the current detecting element is grounded via a first capacitor C1, and is connected to a 5V power supply via a first resistor R1, and is connected to the input terminal of a comparison link formed by two comparators via an RC low pass filter formed by a second resistor R2 and a second capacitor C2, and the output terminal of the comparison link is connected to the 5V power supply via a fourth resistor R4, and is connected to the main control chip. The output end of the current detection element is also connected with the main control chip through an RC low-pass filter consisting of a third resistor R3 and a third capacitor C3 and a diode D1 in sequence.
Specifically, the current detection element is a hall current sensor, and the main control chip is a Digital Signal Processing (DSP) chip. The first capacitor C1 and the fourth capacitor C4 are filter capacitors, the first resistor R1 and the fourth resistor R4 are pull-up resistors, the second resistor R2 and the second capacitor C2 form an RC low-pass filter, the third resistor R3 and the third capacitor C3 form a low-pass filter, the diode D1 is a clamping diode, the U1A and the U1B are differential comparators of a comparison link, and an upper limit voltage and a lower limit voltage are input to the comparison link.
The working principle of the over-current protection circuit of the motor of the electric automobile is as follows:
the Hall current sensor collects three-phase current signals of the motor and converts the three-phase current signals into voltage signals, and then the voltage signals are filtered by a first capacitor C1 and pulled up by a first resistor R1:
one path enters a comparison link through an RC low-pass filter formed by the second capacitor R2 and the second capacitor C2, an output signal of the comparison link is pulled up through the fourth resistor R4 to form a first signal, and the first signal is sent to a digital quantity interface of the DSP chip. If the voltage signal output by the Hall current sensor is between the upper limit voltage and the lower limit voltage, the first signal is at a high level; if the voltage signal is higher than the upper limit voltage or lower than the lower limit voltage, the first signal changes to a low level. The DSP chip can make corresponding action according to the first signal.
On the other hand, a second signal is formed via a voltage clamp circuit (i.e., an overcurrent secondary check circuit) formed by an RC low-pass filter formed by the third resistor R3 and the third capacitor C3 and the clamp diode D1, and the second signal is sent to an analog interface of the DSP chip. The DSP chip can calculate the three-phase current of the motor in real time according to the signal.
Referring to fig. 4, a method for operating the overcurrent protection circuit of the motor of the electric vehicle is described:
when the DSP chip monitors that the first signal is at a low level, the overcurrent is considered to occur, the DSP chip immediately cuts off the PWM signal output of the DSP chip, and only the control signal of the motor, namely the PWM signal is cut off, so that the motor still runs due to the inertia effect in a short time; after the secondary judgment, if the PWM signal is restarted immediately, the operation of the motor is not influenced.
And then, calculating the three-phase current value of the motor according to the second signal, wherein the specific calculation formula is as follows:
wherein: ip is the three-phase current value of the motor; vout is the output voltage of the Hall current sensor; vc is the working voltage of the Hall current sensor; g is a conversion coefficient, is related to the working voltage Vc of the Hall current sensor, and the value of the conversion coefficient can be found in a data manual. Then judging whether the calculated three-phase current value of the motor exceeds a preset overcurrent protection limit value:
and if the overcurrent number exceeds the preset limit value, judging that the overcurrent fault exists, sending an overcurrent fault code to the outside by the DSP chip, clearing the overcurrent number flag bit, and finishing the overcurrent fault processing.
If the overcurrent number does not exceed the preset limit value, the PWM signal output is restarted, and the overcurrent number zone bit is added with 1. Then monitoring whether the overcurrent fault occurs again within the specified time T, if the overcurrent fault occurs again within the specified time T, determining that the overcurrent fault occurs, turning off the PWM signal output by the DSP chip, simultaneously sending an overcurrent fault code to the outside, and finishing the overcurrent fault processing; and if the overcurrent fault does not occur within the specified time T, judging that the previous overcurrent fault is signal interference triggering, after the DSP chip clears the overcurrent time flag bit, controlling the motor and the motor controller system to continue to operate, and finishing the overcurrent fault processing.
In an actual usage environment, the predetermined time T is determined by the electromagnetic interference frequency in the operating method of the protection circuit. In the scheme, 20ms is taken.
In addition, under the actual use environment, the maximum value of the three-phase current of the motor determines a preset overcurrent protection limit value, and further determines the upper limit voltage and the lower limit voltage of a comparison link. In the scheme, the preset overcurrent protection limit value is 2.5 times of the maximum value of the three-phase current of the motor. In the hardware circuit, the upper limit voltage and the lower limit voltage can be obtained by dividing voltage by resistors.
It is worth noting that electric automobile motor excess current protection circuit though derive from the electric automobile field, nevertheless it equally can be applied and industrial motor field and other fields that need to set up overcurrent protection, can carry out corresponding adjustment to the upper limit voltage of hardware circuit, lower limit voltage and the regulation time T in the software as required when specifically using.
In summary, the preferred embodiments of the present invention are only described, and the scope of the present invention is not limited thereto. All equivalent changes and modifications made according to the content of the claims of the present invention shall fall within the technical scope of the present invention.
Claims (3)
1. The utility model provides an electric automobile motor overcurrent protection circuit, once confirms the circuit including the overcurrent, once confirms the circuit including the electric current and gathers component, filter module, two comparators and main control chip in the overcurrent, the electric current gathers component collection motor three-phase current signal and converts it into voltage signal, and this voltage signal inputs to two comparators after the filtering, compares with upper limit voltage and lower limit voltage, and the comparison result is as first signal input to main control chip, its characterized in that: the overcurrent protection circuit further comprises an overcurrent secondary confirmation circuit; wherein,
the overcurrent secondary confirmation circuit comprises an RC low-pass filter and a clamping diode, a voltage signal output by the current acquisition element sequentially passes through the RC low-pass filter and the clamping diode to form a second signal, and the second signal is input to the main control chip; and the main control chip controls whether to output a motor control signal or not according to the first signal and the second signal.
2. The electric vehicle motor overcurrent protection circuit of claim 1, characterized in that: the current acquisition element is a Hall current sensor.
3. The electric vehicle motor overcurrent protection circuit of claim 1, characterized in that: the main control chip is a digital signal processing chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320116678 CN203193255U (en) | 2013-03-14 | 2013-03-14 | Electric automobile motor over-current protection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320116678 CN203193255U (en) | 2013-03-14 | 2013-03-14 | Electric automobile motor over-current protection circuit |
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| CN203193255U true CN203193255U (en) | 2013-09-11 |
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| CN 201320116678 Expired - Lifetime CN203193255U (en) | 2013-03-14 | 2013-03-14 | Electric automobile motor over-current protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112217421A (en) * | 2020-09-01 | 2021-01-12 | 杭州阔博科技有限公司 | Circuit, method and controller for preventing electric vehicle from being started by mistake and electric vehicle |
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2013
- 2013-03-14 CN CN 201320116678 patent/CN203193255U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112217421A (en) * | 2020-09-01 | 2021-01-12 | 杭州阔博科技有限公司 | Circuit, method and controller for preventing electric vehicle from being started by mistake and electric vehicle |
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Granted publication date: 20130911 Effective date of abandoning: 20160726 |
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| C20 | Patent right or utility model deemed to be abandoned or is abandoned |