The history of the creation of the hybrid series-parallel (shunt) regulator/rectifier and the concept of operation

From idea to realization

The use of parallel (shunt) regulators/rectifiers brought with it the problem of constant strong heating of the regulator, regardless of whether the battery is full or empty. The generator windings also operate in maximum heat load. Because of this, failures of parallel (shunt) regulators/rectifiers and stators have become the rule and it is only a matter of time before they fail.

In an effort to avoid unnecessary loading of generators and regulators/rectifiers in parallel (shunt) configuration, we developed in 2002, based on our own knowledge, a serial thyristor regulator for single-phase and three-phase generators. A well-designed combination of thyristors, diodes and a relatively small number of regulation elements resulted in a high-quality and reliable regulator/rectifier. Originally designed as series with parallel (shunt) protection, the regulator/rectifier originally evolved to be purely series. A few years later, an almost forgotten project, surfaced as an ideal solution for a single-phase charge regulator/rectifier on board. A friend had an AC generator on a boat engine and was having problems with the battery charging voltage being too high. For a gel version of the battery, this means a path to destruction and great expense.

Seasonal testing on the boat proved to be excellent and the project went from an idea to a proven version through testing. As a predecessor to this version of the serial regulator/rectifier, a serial regulator with the UC3843 chip was also made (three diodes for minus and three thyristors for plus). This regulator worked well, but had fatal sensitivity to a bad battery. The problem with sensitivity to battery voltage had to be eliminated and the current consumption from the battery at rest had to be minimized. The newly developed circuit not only met these requirements but also had additional properties. Precise battery voltage regulation (0.1V), constant microampere consumption (at rest and in operation) and even resistance to reverse connection of the output terminals to the battery (the housing must be isolated from ground and the engine turned off).

And so we have a virtually ideal regulator/rectifier for motorcycles and outboard motors. The user only has to make sure that the battery is working properly, i.e. that the battery is receiving power from the generator and is charging, and that everything is connected properly.

In the 6th month of 2009, testing of the series regulator/rectifier on motorcycles reaching over 8000 engine revolutions per minute showed that the three-phase series regulator/rectifier remains on due to the inductance of the generator winding. The effect is solely a consequence of the high voltage and frequency from the generator, and the energy in the inductance of the winding fails to discharge, resulting in a permanent DC current on one thyristor by switching the currents from two phases to the third, and the regulator remains on and transmits approximately 50% of the available current. The battery voltage begins to rise uncontrollably. The logical solution was to upgrade the series regulator/rectifier with an independent parallel(shunt) regulator that will operate a short-term short circuit of the generator via the circular connection of three thyristors between the stator phases and thus enable the safe disconnection of the thyristors of the series regulator/rectifier. The parallel (shunt) regulator/rectifier is switched on when the series fails, i.e. at 0.25V higher voltage. The prototype regulator/rectifier is built, installed and working without error. Due to additional elements, the dimensions of the regulator/rectifier are 41% larger in length. Also, the regulation electronics scheme has been improved. Version 2.0 performance has improved voltage stability and better error amplification, and under normal conditions precisely regulates the battery voltage (within 20mV). The voltage characteristic has a negative temperature coefficient of 2.2mV/°C.

From the 4th month of 2010, due to the simple installation of the LED charging indicator, we are starting to offer this option as well. The charging LED indicator lights up when the voltage is lower than the set value, flashes when it is maintained, and turns off when it is too high or the generator is not working. The LED charge indicator can be on the regulator itself or on the wires.

Since July 2012, the regulator/rectifier has been equipped with an LED as standard, which indicates when the regulator has not reached voltage or the stator is connected to the housing.

Since March 2013, the series-parallel (shunt) regulator/rectifier has been improved with better protection in the event of a battery disconnection. The improved protection instantly activates the shunt regulator when the voltage at the output terminals exceeds 40V. This raises the protection of this type of regulator to its highest level. The change does not affect other characteristics of the regulator.

Since May 2014, the operation of the serial voltage comparator has been improved. All battery charging regulators/rectifiers (except parallel-shunt) will have overheating protection as standard, which turns off the serial regulator/rectifier when it heats up above 70°C.

Since July 2014, the operation of the serial voltage comparator has been improved to version 3, and the voltage maintenance is even more stable (10mV). Due to the short and fast thyristor firing pulses, the LED indicator no longer flashes when the regulator maintains voltage.

Since September 2015, the hysteresis of the parallel regulator has been reduced (18mV) to avoid unnecessary load on the stator.

Since May 2018, we have started installing stronger thyristors in the serial part of the regulator/rectifier. The newer generation of thyristors has better heat dissipation and can therefore withstand higher currents.

Since September 2021, the serial regulator/rectifier has also received overvoltage activation in addition to the parallel regulator. The serial regulator/rectifier is activated at a slightly lower voltage, thus ensuring continued battery charging even in the event of an overvoltage on the stator.

Concept and advantages of the hybrid 3FHVSP series-parallel (shunt) regulator/rectifier

A hybrid series-parallel (shunt) regulator/rectifier is more complicated, more expensive and larger than if it were implemented as a complete thyristor series regulator/rectifier. Practically speaking, the larger mass of the cooler reduces the working temperature of the regulator/rectifier and thus gives it a longer lifespan.

The hybrid series-parallel (shunt) concept of the regulator/rectifier can enable satisfactory charging of the battery even when there is a breakdown of the stator to the housing. It's hard to find another regulator/rectifier that can do that. In this respect, the hybrid series-parallel (shunt) regulator/rectifier is perhaps unique. The standard version 3.5 universal 3FHVSP regulator/rectifier 14V-3FHVSP-30A-AX-KS-LI has a wire to turn on the series regulator/rectifier while the parallel regulator is autonomous and permanently active for protection. The condition is that the stator has not lost its voltage amplitude. A short circuit between the stator and the housing is recognized by a reduced voltage on the battery (max 13.1V) which may occasionally go up to 15.1V. The only action that needs to be taken is to temporarily remove the wire (white) for switching on the series regulator/rectifier from +12V and connect it to ground. This prevents the series regulator/rectifier from interfering with the battery charging while the stator is connected to the housing. The protective shunt regulator takes over the voltage regulation. The achieved voltage is slightly higher due to the programmed delay of the shunt regulator, and the required lower voltage on the battery is achieved by riding the motorcycle at a slightly lower engine speed. The damaged stator should be replaced as soon as possible and the wire for switching on the series regulator/rectifier should be returned to where it was connected.

The parallel (shunt) regulator also has the additional ability to instantly activate a stator short circuit if the voltage at the regulator output exceeds 40VDC. This protects the regulator/rectifier control electronics and the motorcycle electronics.

The series regulator/rectifier switches off when the regulator/rectifier overheats above 70°C. This protects the regulator/rectifier from destruction in many situations (mud filling, lack of air circulation, current overload in the event of a stator short circuit to the housing, too high ambient temperature, etc.). After temperature protection became a standard part of the regulator/rectifier, destruction due to poor external operating conditions ceased.

Series and parallel (shunt) regulators/rectifiers have overvoltage protection against high stator voltage that activates their operation. The series regulator/rectifier starts rectifying the voltage in case of overvoltage, and the parallel (shunt) regulator short-circuits the stator in case of even higher voltage from the stator or increased voltage on the battery (>14.7V with a delay, >40V immediately). This ensures that the battery charging does not stop even in conditions of excessively high stator voltage. The regulator/rectifier will then operate as a parallel (shunt) regulator/rectifier.

Disadvantages of the hybrid 3FHVSP series-parallel (shunt) regulator/rectifier

The first disadvantage of this regulator/rectifier is the occasional short-term increase in the output voltage by 0.25 to 0.3V (when the engine speed is over 9000rpm), after which the protective shunt regulator is triggered. However, in practical use, this is difficult to measure with a voltmeter and does not affect the operation of the engine and motorcycle or the durability of the battery at all.

The second disadvantage is the required starting voltage of at least 6V on the battery for the regulator/rectifier to operate. Although this seems like a disadvantage, a 12V battery with such a low voltage is not even capable of receiving rectified current from the stator and an overvoltage would occur. So it is not a real disadvantage. Also, if there is no battery connected, the hybrid series-parallel (shunt) regulator/rectifier will not work, which is a good thing.

The third disadvantage of the hybrid series-parallel (shunt) regulator/rectifier is that, due to its series principle of operation, it sometimes burdens the stator, and a much higher voltage develops on the stator than with a parallel (shunt) regulator/rectifier. When a structurally impermissibly high voltage from the stator occurs, the regulator/rectifier can switch to an exclusively parallel (shunt) mode of operation (but battery charging will continue). For special cases, we make the modification 14V-3FHVSP+30A-AX/BX-KS-LI, which additionally allows a higher voltage from the stator. However, due to the high voltage at the stator output, there is an increased probability of the stator insulation breaking through to the housing. It happens here and there. It will be more common if the same stator was left when replacing the regulator/rectifier. This happens with other regular series regulators/rectifiers, not just this type.

It is obvious that in a normal situation, the listed disadvantages of the hybrid 3FHVSP series-parallel (shunt) regulator/rectifier will not come to the fore, and in fact these are not important disadvantages.

The first and only commercially available series-parallel (shunt) regulator/rectifier

Although 16 years have passed since the beginning (2009) of the commercial production of hybrid series-parallel (shunt) regulator/rectifier, we are still the only world manufacturer of hybrid series-parallel (shunt) type regulator/rectifier. Perhaps one of the reasons is that it is necessary to carry out precise calibrations of the two regulators and ensure stability during heating by design so that there is no mutual collision during operation, which could unnecessarily increase the current from the stator. We also have modifications of the 3FHVSP regulator/rectifier (Dual point and K2 option) which have some better characteristics. However, the basic version is so good that in 99% of cases there is no need for modified versions.

User experiences are great. Stator heating is reduced, and stator burning due to overheating no longer exists. The regulator/rectifier heats up a bit and replaces the original factory regulators/rectifier without any problems. It also proved to be an excellent replacement for the more expensive serial Shindengen regulator/rectifier SH847. Failures of the hybrid series-parallel (shunt) regulator/rectifier in the last 5 years of production are almost non-existent, and we estimate them to be less than 0.2% in the warranty period and outside the warranty period. There are many stories of satisfied users. The reason for the reliability is the installation of substantially stronger diodes and thyristors, a larger housing, good insulation from moisture, control electronics without parts that age rapidly at elevated temperatures (eg electrolytic capacitors) and quality assembly.

The possibility of upgrading the serial regulator/rectifier for working at high machine speeds

The concept of a hybrid series-parallel (shunt) regulator/rectifier gives the theoretical possibility that our parallel (shunt) protection regulator can be added to the existing series regulator/rectifier. For example The Shindengen SH775 could be upgraded and turned into a hybrid compound for high engine revs. The parallel (shunt) regulator for upgrading has only three thyristors and control electronics. It is connected to 5 wires in parallel with the existing series regulator/rectifier. Current consumption at rest is 68uA. One big problem is that it should be achieved that the adjusted voltage of the parallel (shunt) regulator is 0.25V higher than that of the series regulator/rectifier in the entire operating temperature range. Which means that the added parallel (shunt) regulator must be matched and calibrated for the specific series regulator/rectifier.

Versions and documentation:

⦁ 14V-3FHVSP-30A-AX/BX-KS-LI - for lead batteries

⦁ 14V-3FHVSP-30A-AX/BX-K2-LI - for AGM batteries or when the regulator is further away

⦁ 14V-3FHVSP+30A-AX/BX-KS-LI - for 280VAC voltage from the generator

⦁ Advertising leaflet with floor plan of the case in M1:1 scale and a list of motorcycles on which the 3FHVSP regulator is already installed

⦁ Advantages of the series regulator

⦁ Comparison of 3F HVSP regulator with Shindengen SH847

⦁ What to do when the voltage regulator on a motorcycle often burns out?

⦁ What to do when the stator on a motorcycle often burns out?

⦁ Control of the charging voltage of the 12V battery

⦁ Instructions for a quick solution to too low battery voltage