The protection function is to prevent over-discharge of the commutation power tube and power supply in the controller, and when the elderly leisure tricycle is in operation, the circuit will take it according to the feedback signal when there are some faults or misoperations that may cause damage and other faults. Safeguard. The basic protection functions and extended functions of electric vehicles for the elderly are as follows:
1. Brake power off
The two caliper brake handlebars on the handlebar of the leisure tricycle for the elderly are all equipped with contact switches. When braking, the switch is pushed and closed or disconnected, thus changing the original switch state. This change forms a signal and sends it to the control circuit, and the circuit issues an instruction according to the preset program to immediately cut off the base drive current, cut off the power, and stop supplying power. Therefore, it not only protects the power tube itself, but also protects the old motor, and also prevents the waste of power supply.
2. Undervoltage protection
This refers to the voltage of the power supply. At the final stage of discharge, under load, the power supply voltage is close to the “end-of-discharge voltage”, and the controller panel (or instrument display panel) will show that the battery is insufficient, which will attract the attention of the rider and plan his itinerary. When the power supply voltage has reached the end of discharge, the voltage sampling resistor will feed the shunt information to the comparator, and the protection circuit will issue instructions according to the preset program to cut off the current to protect electronic devices and power supply.
3. Overcurrent protection
Exceeding the current limit may cause damage to a series of components of the motor and circuit, or even burn out, which should be absolutely avoided. In the control circuit, this kind of overcurrent protection function must be provided, and the current will be cut off after a certain delay when the overcurrent occurs.
4. Overload protection
The overload protection is the same as the overcurrent protection, and the load exceeding the limit will inevitably cause the current to exceed the limit. The load capacity is specifically indicated in the manuals of electric vehicles, but some riders either do not pay attention to this point, or intentionally overload it with the mentality of trying it out. If there is no such protection function, it may not necessarily cause damage in any link, but the switching power tube is the first to bear the brunt. As long as one of the power tubes of the brushless controller is burned, it will become two-phase power supply, and the old motor will become weak when running. The traveler can immediately feel the abnormal pulsation; if he continues to ride, then the second and third power tubes will be burned. If the two-phase power tube does not work, the motor will stop running, and the brush motor will lose its control function. Therefore, overcurrent caused by overload is very dangerous. But as long as there is over-current protection, the circuit will automatically cut off the power supply after the load exceeds the limit, and a series of consequences caused by overload can be avoided.
5. Underspeed protection
It still belongs to the category of overcurrent protection, and it is set for the brushless control system without the function of starting at 0 speed.
6. Speed limit protection
It is a unique design control program for elderly power-assisted electric bicycles. When the vehicle speed exceeds a certain predetermined value, the circuit stops supplying power and does not provide assistance. For electric electric vehicles for the elderly, the unified speed is 20km/h, and the rated speed and control circuit have already been set when the vehicle motor is designed. Elderly electric vehicles can only run at a speed not exceeding this speed. The position of the controller does not affect the performance, it mainly depends on the intention of the designer. But there are several principles: (1) When the operation is allowed; (2) When the overall layout is allowed; (3) When the line layout is required; (4) When the supporting facilities are required.
The output speed regulation signal is a voltage signal, and the output voltage of the Hall turntable depends on the strength of the magnetic field around the Hall element. Turning the handle changes the magnetic field strength around the Hall element, which also changes the output voltage of the Hall handle. Then input this voltage into the controller, and the controller performs PWM pulse width modulation according to the magnitude of this signal. Therefore, the ratio of on-off of the power tube is controlled to control the speed of the motor.
Post time: Mar-13-2023