Energy-saving motorcycle rectifier regulator

The electric energy on the motorcycle is supplied by the magneto on the vehicle. The output voltage of the magneto is stabilized by the silicon rectifier regulator on the vehicle, and then supplied to the electrical appliances on the vehicle and charged to the battery. At present, many domestic motorcycles widely use parallel switch voltage regulators, as shown in Figure 1. When the output voltage of the magneto exceeds the rated voltage, the device uses the conduction of the thyristors SCR1 and SCR2 inside the silicon rectifier regulator to clip the output voltage of the magneto to achieve voltage stabilization. In this way, during the day, most of the electrical appliances on the vehicle do not use electricity, but the thyristors are in the conduction short-circuit state most of the time, and most of the electric energy generated by the magneto is wasted and consumed in the form of heat. The consumption of this energy is ultimately the consumption of fuel. It is estimated that a Wuyang Honda WH125T vehicle consumes at least 30L of fuel on the silicon rectifier regulator in a year (calculated based on 1 hour of operation per day), which is quite considerable).

If there is a device that can cut off the power supply circuit of the generator when the electrical appliances on the car are not in use and the battery is fully charged, the purpose of saving fuel can be achieved. This device is designed based on this idea. After testing, it has fully achieved the expected effect.

How it works 

The circuit of this device is shown in Figure 2. The AC voltage output by the magneto is rectified by diodes D1~D6 and becomes a pulsating DC voltage, which is output in two ways. One way is a typical transistor series voltage regulator circuit composed of Q1, Q2, Q3, R1, R7, DW1, and C2, which outputs a 16V voltage after voltage regulation, and charges the battery through D8; the other way is isolated by D7, filtered by C1, and regulated by IC1 to obtain a 12V DC stable voltage to power the operational amplifier IC2, and connected to the ② pin of IC2 through resistor R6 as a reference voltage. The battery voltage is divided by R4 and R5 and sent to the ③ pin of IC2 as a comparison voltage. When the battery voltage is lower than 14.4V, the comparison voltage added to the ③ pin of IC2 is lower than the 12V reference voltage of the ② pin, the operational amplifier outputs a low level, Q4 is cut off, and Q1~Q3 work normally and output 16V voltage. When the battery voltage is higher than 14.4V, the comparison voltage of IC2's pin 3 is higher than the reference voltage of pin 2, IC2 outputs a high level, Q4 is saturated and turned on, shunting the current flowing into the base of Q3, causing the output voltage of Q1Q2 to drop significantly, D8 is cut off, and the battery charging and power supply to the electrical appliances are stopped. At this time, all the electrical appliances in the car are powered by the battery. When the battery voltage is lower than 14.4V again, IC2 outputs a low level again, and Q1 and Q2 output normally again. Obviously, when the battery is fully charged, the magneto works almost in a no-load state, unlike the conventional silicon rectifier regulator, which is in a large load short-circuit state, thus achieving the purpose of energy saving. In the circuit, R3 is the positive feedback resistor of IC2, R7 is used to trickle charge the battery when Q1Q2 is cut off, and the role of D9 is to ensure that the slight zero drift output of some operational amplifiers will not cause Q4 to turn on and cause malfunction.

Circuit debugging

As long as the components of this circuit are good, there is generally no need to debug after welding. If you want to change the termination charging voltage of the battery, you only need to change the resistance value of R4 or R5, that is, change the sampling voltage of IC2 pin ③.

Installation and Usage

Q1 and Q2 need to be equipped with heat sinks when installed. After the circuit is connected, it should be encapsulated with epoxy resin. Remove the original silicon rectifier regulator on the car, and connect the three terminals A, B, and C to the output terminals of the magneto. If the original magneto is a single-phase motor, just connect any two terminals. D and E are connected to the output terminals of the original silicon rectifier regulator. If the battery used in the original car is 6V, IC1 and DW1 in the circuit should be replaced with 78L06 and 9V regulator tubes respectively, and the other components do not need to be changed.