Electric bicycle charger
To lead-acid battery electric vehicles, nickel cadmium batteries to add energy, through the charger. Many different types of chargers. Generally distinguish between whether the frequency transformer can be divided into two broad categories. Cattle commonly used high-power frequency transformer ring. Although low efficiency, but current (available at 30A), and reliable. Electric three-wheeled cargo, without exception, to use it, and 30Ah batteries are mostly used the following switching power supply technology, thus improving efficiency, get rid of the bulky low frequency transformer. Electric bicycle charger at 2A maximum charge current is mostly about.
1. Using switching power supply technology for electric bicycle charger
(1) Shandong GD36 Charger
Circuit diagram shown in Figure. The charger for the half bridge charger. The main performance indicators: Input voltage :170-260V; output voltage: 44 V (adjustable); Maximum charge current: 1.8A; floating charge current: 200 ~ 100mA.

1) circuit
The main mains charger rectifier filter circuit, self-excited half-bridge converter plus he excited, PWM control, voltage control, current control, output rectifier filter six parts.
After filtering the mains rectifier diodes D1 ~ D4 220V/50Hz bridge rectifier, filter capacitor C5 ~ C7 to get around 310V DC voltage, as the switching converter power supply.
Self-excited half-bridge output circuit plus he excited mainly by Q1, Q2, B2, B3 and other components.
Self-excited to start the circuit is characterized by a self-excited start, the control circuit to provide the necessary auxiliary power by itself, without a separate. Self-excited oscillation is generated by core saturation, the specific process is: power, C5, C6 on the 150V voltage by R5, R7, R9, R10 to switch Q1, Q2 provides base bias. TR5 set by the bias and the micro-Q1 turns on, the drive transformer B2, 2 - 4 2 winding polarity is induced in the foot now, 4 foot negative voltage, so 1 - 2 1 foot winding induces a positive, 2 negative voltage pin added to the emitter of Q1, Q1's conduction speed. This is a very strong positive feedback process, Q1 quickly saturated conduction. At the same time, 3 - 5 3 foot winding induces a positive, 5 foot negative voltage, so that Q2 closed.
Q1 saturated conduction, the 150 voltage to B3 1 - 2 storage charge the main winding, coil current and the magnetic field it produces increases linearly with time. But when the magnetic flux density Bm increases to the saturation point, the inductance decreases rapidly, Q1's collector current sharp increase in the rate of increase than the increase of its base current, Vce increasing, so the Q1 out into the enlarged area saturated, to promote the transformer B2, 2 - 4, 1 - 2, 3 - 5 winding induced voltage will be reversed. This is also a strong positive feedback process, the result is close Q1, Q2 saturated conduction. Since then, this process is repeated and the formation of oscillation.
Works as follows:
He oscillation: the process of self-excited oscillation, B3 of the secondary output voltage through D9, D10 full-wave rectifier, C19 filter, PWM control circuit to establish the necessary working power chip TL494. TL494 to work, the Q3, Q4 output phase of the PWM pulse is 180 °, the B2 6 - 7, 7 - 8 winding induction to 1 - 2 or 3 - 5 winding. So Q1, Q2 will be turned by the self-excited PWM pulse excited in his turn driven by conduction. B3 secondary 9 - 7, 9 - 8 winding output voltage is full wave rectified by D15, C21 filter by +44 V voltage to charge the battery.
D6, D7 are two clamping diodes. Protect the switch Q1, Q2. Protection mechanism is the primary flyback relief B3 and leakage inductance energy storage, to eliminate anti-peak voltage. When the Q1 into cutoff and by the turn has not yet turns on Q2, D7 conduction, the flyback energy regeneration to charge C6; when Q2 turns into a cut-off while the then not turns on Q1, D6 conduction, the flyback energy regeneration to the C5 charge. On the one hand to eliminate the anti-peak voltage, on the other hand because of the energy back to the sending power flyback and greatly improve the power efficiency.
TL494 PWM control to the core composition. C12, R19 and the internal oscillation circuit is formed when these two parameters as icons RC component values, the oscillation frequency of about 50kHz. (13) feet to +5 V, pulse output mode is set to push-pull output. 8, (11) push-pull output pin pulse width modulated, amplified by the evacuation of half-bridge driver circuit output stage, control, Q1, Q2 turns conducting.
R20, R24 partial pressure control of dead-end set foot 4 potential, limit the maximum on-duty cycle less than 45%. C18 is a slow start capacitor, connected to the power, C18 both ends of the voltage is zero, 4 the foot of the potential is approximately +5 V, the output pulse duty cycle is zero. With the C18 charge, 4 pin voltage decreases, conduction duty cycle increases, the output voltage gradually controlled.
Voltage and current control: R26 and R27 is a negative feedback voltage sampling resistor, R26 and R27 divider, the output voltage sampling, added to the TL494 pin for voltage control of 1. R3 is the current sampling resistor R13 added by sampling the voltage of the TL494 (15) feet for current control. Current control is real control output voltage.
Push-pull drive: from Q3, Q4, B2 and other components. This is a typical transformer push-pull power amplifier circuit. D11, D14 role and D5, D7 similar to the protection of Q3, Q4, the B2 primary energy flyback echo power.
Mainly by the charge status indicator op amp LM358, LED1, LED2 and other components. When the charge current is large, the current sampling resistor R3 to the top of the voltage well below potential, LM358's 2 3 feet lower than the potential of the foot potential, 1 pin output high, battery charge indicator light LED1; when the charge current is small (less than 200mA) when, +5 V through R36, R30, R3 divider, R3 voltage slightly higher than the upper ground, LM358 2 3 feet feet above potential, 1 pin output low, battery charge indicator LEDl off, 7 pin output high. in full, indicator LED2 is lit. During the charging process in the presence of a LEDl, LED2 lit while the transition state.
2) Debugging
Open circuit output voltage output voltage 44V, R26 or R27 can be calibrated to change this value. 44V low voltage should be higher than the summer of 1V, the battery voltage if it is even lower gel, or they might charge drum package.
Short-circuit output current output current of 1.8A, change the R13 can be calibrated to this value.
Debugging when the charge status indication when the current is 200mA, the battery is full LED LED2 should begin to light up. R30 can be calibrated to change the state.
3) Summary
Many half-bridge charger to TL494 as the core structure is very similar, TL494 contains internal oscillator, saw the formation, PWM, the basic unit of operational amplifier circuits, voltage regulator and current limiting amplifier feedback is added to end. Another comparison to an IC for the secondary, the current sub-control work to the power of these integrated circuits, power start, start the power supply circuit for them, and then gradually build from the auxiliary power supply stable power supply for these circuits work provide energy.
Some of these chargers similar failures, for example, have a lower no-load output voltage, with a load output disappeared. TL494 most damage, or power circuit failure. Self-excited load instructions are output normally, but failed to establish the normal control system, with a load from the shock condition is destroyed to stop vibration, the output voltage disappears.
For no-load half-bridge output charger, pipe damage in the insurance case, the first two switches are suspected breakdown, while replacing the NPN tube, check for damage 2.2Ω, and other peripheral devices. After the power check the replacement parts are still empty, but in the city, an ordinary series with the input 100W incandescent bulbs, when switched on, shiny look dim incandescent bulbs, while half-bridge normal charger LED light of various , illustrates the basic repaired, other projects can be a; if not dimmed incandescent bulbs lit, indicating that the charger has other faults.
There is a kind of damage due to switch TL494 good, positive channel until the switch back to normal. But the regulator feedback system problems. TL494 output to switch the pulse duty cycle control (increase), resulting in damage to switch. Therefore, the best switch in the exchange, the use of power supply to the IC power supply, analog feedback system change in feedback voltage regulator, with the oscilloscope is the corresponding duty cycle changes.
Maintenance charger safety issues are important, we must find out where the circuit with electricity, where the re-start with no electricity, do not touch the internal circuits and components live. Test with a multimeter, you should unplug the battery and mains plug, and then to discharge the capacitor, the discharge of filter capacitor can be used for normal incandescent bulbs.
The adjustment of the charger is very important, direct impact on battery life. The 12V battery, for example, float voltage 13.5V ~ 13.9V for the long term, generally no more than the output voltage 14.2V, or easy to make the battery water loss. Need to be reminded of is: when the pressure in the control gel battery charging voltage should be lower; voltage should be lower in summer, lower rate for each cell (12V battery 6 cell) per ℃ 4mV. Maintenance charger, the key is to find the voltage negative feedback voltage sampling resistor. Reduce the resistance of proficiency in the upper half of the sampling resistor, the output voltage is reduced; increase the resistance of the upper half of the sampling resistor value, the output voltage increases. Or, conversely, reducing the resistance the lower half of the sampling resistor, the output voltage increases; increase the resistance of the lower half of the sampling resistor, the output voltage lower it. Second is to find the charge current sampling resistor, and current sense comparator, the phase change the charging current control method.
References ground potential in the analysis of current sense comparator circuit is very important. This is because the charger current sense comparator IC is a single power supply, grounding one end of the comparator, the comparator the other end of the sampling resistor, the voltage on the sampling resistor is generally a negative voltage.
(2) a single shock of a company in Shijiazhuang Charger
Charger schematic diagram shown in Figure 13. Chargers start a single-excited half-bridge circuit and, generally taken directly from the rectified mains DC smoothing filtering, integrated circuits also UC3842, UC3845 and UC3844N-based, there is also more compact circuit three-terminal integrated switching TOP226 block, UC38xx single-output PWM current control is a special chip. Widely used in computer monitors power, electric car chargers and other power products.

UC38xx and TL494 similar, with the internal oscillator (OSC), the error amplifier, pulse width modulation (PWM), PWM reference voltage generator and other necessary special chip inside the circuit. Also has three features, totem pole output circuit, output current up to 1A, can directly drive the power switch VDMOS tube: adjustable with an internal reference power supply. Can be under-voltage lockout; this with lock PWM, can be by-pulse current limit, also called by week (of) restrictions.
Figure 13, R18, D5, N5 and other components to start and power supply circuits. Power moments. Mains smooth DC rectifier filtered through R18 to the UC3845 7 feet to start the power supply, D5 anti-bias cut-off time. UC3845 work, switch the windings are inductive voltage transformer, the secondary winding voltage is rectified by D4 to regulators for the N5, D5 turn, to provide a stable working voltage UC3845 complete the start-up and power supply. LM393 is a deformation of the figure Schmitt voltage comparator, as mains voltage protection, over voltage when the mains, the comparator flip, 1 feet were low, D3 turn off the UC3845. Output voltage of the negative feedback system consists of optical coupler, the power base N6, RV1, R27, R26, R23 and so on. Regulated process: for some reason the output voltage rises, flows through the optocoupler LED current increases, light intensity increases, phototransistor optocoupler increased conduction. Resistance decreases, so that the voltage increases UC3845's ② feet, reducing the PWM duty cycle, low output voltage. Conversely, increasing the PWM duty cycle, the output voltage is pulled high, the output voltage to play the role of automatic stabilizers.
1) over-current (overload) protection
Switch over-current signal from the resistors R3, R4. Once the switch over-current, UC3845's 3 pin voltage exceeds 1V, the internal circuit will turn off the output, to achieve over-current (also called overload) protection. Increase the sampling resistor, is reduced from the current action point control, power output is also reduced accordingly.
2) over-voltage protection
Power output of the LM339 voltage comparator four A, B, C, D are fixed in the reverse-side potential of +5 V. A and B detection output voltage when the output voltage is low, the initial phase of the charge, A the 2 feet low, low-voltage lights LOW light, B the ① feet low and high pressure HI is also bright lights; When the charging voltage is increased. A flip, low-voltage lights LOW off, high pressure lamps HI continue to shine, when the battery is full, the battery voltage increases, B turn, 1 pin is high, high pressure lamps HI off. Meanwhile, C's (13) pin is high, D (14) feet high, N7 turn, J1 pull, J1-1 (normally closed) off the sampling resistor R4 access, increasing large a current sampling resistor, the output current began to decrease from the control, into the float charge stage. N4, W1, R8, R7 constitute a 12V power supply, provides power for the 12V relay.
(3) days to TN-1 negative pulse charger smart
Figure 14 is the day to TN-1 negative pulse charger schematic smart. The main part of the charger is a typical half-bridge two chargers, and chargers described above essentially the same as in Figure 12. This introduces a negative pulse charging part of the work. This part of the circuit by the discharge switch, negative pulse loading control, the pulse oscillator composed of three parts.

Discharge switch is a transistor Q6, Q6 turns on, its collector and emitter short-circuit the battery, battery discharge. Q6 off, battery charge recovery. Q5 and Q6 are directly coupled, commonly known as Darlington. Q6 negative pulse control by the load and the oscillator joint control. Negative pulse control by loading the C and D constitute the IC3. D connected as inverter (circuit, two input NAND gate in parallel as a non-door), only C, when both inputs are high, 3 pin is low, the RP-D guide to Q6 pass, to the battery discharge. C, 2 feet per second from the multivibrator 1 (pulse width 3ms) positive pulse, C, 1 feet from the two-phase current detection circuit IC2 of 1 feet, constant current charging 1 pin is high. At this point, the negative pulse is applied.
Pulse oscillator, A and B by the IC3, and C24, C25, two 100kΩ resistors constitute a typical multi-harmonic oscillator, the charge and discharge time constants of different high 3ms, low 1250ms. Negative pulse charging, can increase the charge acceptance, lower charge temperature; country also can eliminate the argument sulfide extend battery life. The charger in the discharge and did not disconnect the charging circuit.
2. Has the power frequency electric bicycle charger transformer
(1) Happy card KLG smart charger
Happy card KLG intelligent charger is a three-wheeled cargo with a common power transformer charger cattle ring. Circuit diagram shown in Figure

Transformer T has a tapped primary. There are two separate secondary windings. Below is a 14V auxiliary power winding. To the control circuitry; top charging winding has a tap for 36V battery charging use. Above is for the 48V battery (not used) . Electricity through normally closed relay contacts connected to the primary J-1 when the tap A is the constant current charging position, output 43.2V; through the normally open relay contacts connected to the primary top of B, is the trickle charge location, Output 37.5V ~ 43.2V.
U3, G2 formed battery voltage detection circuit retarded, battery voltage through the voltage sampling resistor W2, R2 and R3 add U3B of 5 feet, when the battery voltage rises above 43.2v while, U3B flip, 7 pin output high, U3A flip, its 1 pin output high, leading to G2 turns on, the U3 reference potential drop, resulting in hysteretic latchup. At this time of 1 the U3A pin output high, G1 conduction, the relay J is energized, normally open relay contacts connected to the B point, enter the location of the trickle charge, output 37.5V ~ 43.2V. W2 can change the switch to adjust voltage. R6, C6 is the integral circuit, the delay for a minute or so.
The charger for 48V battery charging, just make two changes: charge the main winding tap change received from the top; increase the voltage of the upper half of the sampling resistor. If necessary, replace the voltage meter.